WM8880 A70M dead tablet?

[DeepestBlueDragon]

I've been given a generic looking 7" Android tablet. On taking it apart, it would seem to have a WM8880 CPU. Printed on the board is "A70M V3". It doesn't seem to charge over USB, instead it has a 5v adapter with a very small barrel jack. When the power button is pressed, a green LED lights up for a few seconds, then turns off. That's it.

I'm wondering if it's had a bad flash in the past and just can't boot up. Is there some way to force a flash on these tablets? I'm fairly handy with a soldering iron as long as what I'm soldering to isn't too small! I've tried putting a ROM on an SD card and powering it up but it doesn't seem to do anything.

Any help appreciated!

 

[Traveller]

Even on a bad flash the device should boot, if only to display the device's logo, if it has one. Yours is more likely a case of a very dead battery. If the previous owner of the tablet did not give you the AC adapter ask them if they have it.

Just don't be surprised if, once you get it working, you discover that the version of Android on the tablet is too old to be useful. The bulk of the devices on the market that used this processor appeared to run Android 4.2 to Android 4.4, and most apps - especially favorites like Netflix - require Android 5.0 or later.

 

[DeepestBlueDragon]

I had it on charge for a day before I posted so unless the battery is entirely dead, it should have enough to power it on. I would hope it would power on just from the AC adapter; my Nexus 7 tablets will power on as long as the battery is present, even if it's completely dead.

I'm not worried about the version of Android; I got this (and a couple of other) similar tablets for free. I have much more modern devices for my own regular use!

Are there instructions anywhere for forcing a flash?

 

[Traveller]

Unfortunately, probably not. The simple truth is that unless you have invested in a tablet ecosystem, e.g. Samsung or Amazon, possibly Lenovo, your tablet isn't going to have any meaningful support. So, no resources on how to use it, no resources on how to fix it, and most importantly, no firmware to download for it. This is why most Android tablets can be found so cheap.

 

[DeepestBlueDragon]

Updating this.

There are serial pads on the rear side of the board (the side that faces the back of the screen). These are unmarked, but it's possible to find out what does what through trial and error. Thankfully, I didn't need them. I disconnected the battery, left it for a while and reconnected; it came right back to life.

As for ROMs, there are MANY out there. These tablets were mass produced with a huge variety of internal configurations - different touchscreens, different touch controllers, different LCD screens, different RAM, different flash. The common element is the WM8880 chip.

Mine has an A70M v3 2013-09-15 mainboard. It has the WM8880 CPU, paired with 256Mb RAM (2x 128Mb SpekTek chips), 4Gb flash (SKHynix), VIA VT1603A audio controller, Silead GSL1680 touchscreen controller, DE-Z7Z735 touchscreen and 7300101466 LCD panel.

I need to find (or build) a ROM that supports all of my hardware. These ROMs aren't the same as ROMs you'd find for (for example) a Samsung Galaxy or a Google Nexus, where you flash recovery, then flash the ROM (a single file) from recovery. These WM8880 tablets flash using an SD card that has the contents of the ROM unpacked with plain text install scripts and config files. This allows a certain amount of flexibility (and ease of use) when putting together your own ROM, as you can mix and match the different packages that provide support for the different hardware builds. I haven't yet figured out how to configure the config file; it's mostly plain text but I haven't figure it out yet.

So for anyone else who's finding this post from a Google search etc... Download all the ROMs you can find and look in the config folder for the file that matches your device's hardware. Rename the file and put a + symbol as the first character. Turn the tablet off. Copy the entire FirmwareInstall onto an SD card. Insert the SD card in the tablet. Hold volume - and power until the screen turns on. You may be asked to confirm that you want to flash, press the key indicated to confirm. Let it do its thing and remove the card when prompted. If the screen resolution is wrong, wait for ten minutes then remove the card - that's long enough for it to flash. When you've done a few you'll be able to figure out when you can remove the card by watching the on-screen messages.