My Daughter has one of the A500 tablets, it's been a great tablet - although it's dual core and nothing special compared to the current market it's always been nice and nippy, has front and rear cameras, 16GB of storage, a nice solid build and up to now .. reliable.
We turned it on to find it stuck at the Acer logo, nothing would shift it and it was clear something was wrong.
A quick whizz around the web and some suggestions, one is to go into a recovery mode that clears the cache and restores the system.
To do this you make sure the screen orientation switch is off (to the right) , hold Volume + and Power, when it buzzes, release Power but keep holding the Volume button, quickly switch the screen orientation switch.
A message pops up on the top left saying it is erasing cache, release the buttons and after clearing the cache it reboots.
In this case it didn't, still stuck at the Acer logo.
There are suggestions that it's either
1) A corrupt loader or Operating system
2) A hardware fault.
One solution is to go on the web and get some OS roms, you rename the rom to update.zip (it must be lower case and that file name), pop it on an SD card and then boot into a different recovery option.
To do this you hold Volume - and power, when it buzzes release power, it tries to load recovery from SD card.
I get an android chappie with a rotating logo then one on his back with a red triangle - things are clearly not good.
In addition, some roms are encrypted so you need the Acer decrypt program, I ran this in Wine (windows emulator) and it decrypted them fine, if you can double click the update.zip and it opens, revealing the files inside then it's not encrypted.
I tried several roms (perhaps 10) and some seemed to get a little further than others.
There is a third mode, the unit can go into a loader mode (APX) which puts it in a position it can accept a full update.
To do this I need my CPU ID, the only problem, I can't power up to get it.
The device isn't seen in lsusb so I make a quick amendment to /etc/dev/rules.d/51-android.rules
Adding two lines of code
SUBSYSTEM=="usb", ATTR{idVendor}=="0502",ATTR{idProduct}=="3325", MODE="0666", SYMLINK+="a500"
SUBSYSTEM=="usb", ATTR{idVendor}=="0955",ATTR{idProduct}=="7820", MODE="0666"
Re-start udev and I can see the device now reporting as an Nvidia device.
lsusb
Bus 002 Device 024: ID 0955:7820 NVidia Corp.
I found a great guide on running a simple script, it then reveals your CPUID - here.
In my case I'm running a 32 bit OS (I should really upgrade to 64 bit but it never crashes and I've never needed to reload my server OS EVER).
so in my case I replace a printf command with one for 32 bit OS.
My file looks like this, I created a file called cpuid.sh
pasted this code in
#include
#include
#include
int main(void)
{
unsigned char data[64];
int received_length;
int r = 1;
libusb_context* ctx = NULL;
libusb_device_handle* dev_handle = NULL;
libusb_init(&ctx);
dev_handle = libusb_open_device_with_vid_pid(ctx, 0x0955, 0x7820);
if(dev_handle)
{
r = libusb_bulk_transfer(dev_handle, 0x81, data, sizeof(data), &received_length, 10000);
if (r == 0)
{
if(received_length == 8)
{
printf("uid: %#016lx\n", *(uint64_t*)data);
}
else
{
r = 1;
printf("Error: We got %d bytes of data instead of the 8 bytes we expected...\n", received_length);
}
}
else
{
printf("Error: USB read failed!\n");
}
libusb_release_interface(dev_handle, 0);
}
else
{
printf("Error: Failed to open device!\n");
}
libusb_exit(ctx);
return r;
}
Then you chmod +x the file so you can run it i.e
sudo chmod +x cpuid.sh
Before I can run it I need to put the A500 into APX mode, to do this power down (hold the power button), then put a paper clip in the reset hole, press and hold, press and hold power for 3 seconds, release power (keep the reset button pressed), hold reset for 1 more second then release.
It sound complex but it's easy to do, it's just holding reset for 1 second longer than power.
Now I can run the cpuid script to see if I can extract this out.
Run it with administrator permissions (./ means run it HERE i.e this directory)
sudo ./cpuid.sh
It creates a file called apx.c
run that by just typing
./apx
And you see your CPUID (you see here the command being run at the end of my directory location)
kevin@server:~/Desktop/A500/A500_fw$ ./apx
uid: 0x037C61C141C00257
So now I have a CPU ID, this means I can use a full restore option - this needs a CPU ID to lock the build to the system and is unique.
I then looked at using nvflash with bootloader_v9.bin, I saw issues in that it formats the memory in the tablet - partition 4 then puts the bootloader in but I had errors when I tried to format, clearly the machine was trying but things were going to be difficult.
Looking around there are many solutions to this, it's quite difficult to find what boot loader options you need and matching this to roms etc. so I found one solution that offered perhaps the simplest, it puts the machine back to Android 3 then you can perform standard upgrades to return to Jelly Bean.
This
solution runs in windows and runs quite a simple process.
This is an Euu package requiring APX mode - you must have your CPUID to be able to use these.
Just ignore the other roms (which I tried anyway), if you have CPUID and can get into APX mode then scroll down to locate the EUU roms and get that one.
Basically you launch the program (I just clicked the DotnetDetector and this launched it), DON'T plug the tablet in yet.
It would normally locate the firmware you are on then find the latest firmware but without a tablet connected it then goes into a fall back mode, offering to update a non functional tablet.
At this stage you click OK then put the tablet in APX mode and connect USB.
You need to supply CPUID and it's not 100% clear in what format, I found it does NOT need the 0x at the beginning so paste the CPUID without.
I also found if you make an error and it fails to close the program and reboot the tablet, it seems to fail always if the first entry is wrong.
The updater advises this will take about 10 minutes, you see the tablet soft boot into APX loader mode and the files downloaded.
At the end just reset the tablet - I popped a paper clip into the reset hole.
The tablet booted into native Android 3.xx, I connected on Wi-Fi and checked for updates, I think it total I had 4 updates.
The tablet is now up and running, fingers crossed it was just a combination of the unit having low power and my Daughter writing files to it that corrupted it.
Great respect to the people who published the web sites, they explained a great deal but putting my experience down here cuts down about 40 hours of messing about, you can do this now in about 2 hours, even less if you have your CPUID.
One word of advice, if you get your CPUID - PUT IT SOMEWHERE SAFE then you can skip right to the end and reload in 10 minutes.
Update : I didn't realize until an hour or two later that it only updated within Android 3.xx , to go up to Ice Cream Sandwich log into the Play store and look for ICONIA TAB UPDATE ENHANCEMENT, install this then when you check for Android updates (settings, About phone) you get a prompt to upgrade to ICS.
