Recently one of my friends brought me bricked Google Nexus 7 tablet. According to his description, he let his device to discharge completely and it wouldn’t turn on nor charge.
First I checked most obvious thing, which is Micro USB charging port. They are not so sturdy, so it’s always good to check connectivity on to port if device will not charge. It did however conduct current and after checking pinout I was able to determine that both cells have no charge whatsoever (0v).
Partial pinout of Nexus 7 battery connector showing cell 1 and 2 connections.
As there is no charge at all, battery chipset might not be able to boot up or haven’t shutdown correctly. I decided to try providing current straight to the battery to see if I can charge it this way.
After stripping insulation from USB cable I had laying around, I connected jumper cables to black and red strands and attached them to battery connector. Make sure to disconnect battery from device before attempting this. Wrong voltage can destroy tablet’s sensitive electronics.
Be sure to connect your makeshift cable to tablet first and then to the charger or USB port.
Jumper cables connected to pins delivering current to cell 1 of two cell battery. (Orange jumper cable connects to black strand in spliced USB cable, I just run out of black jumper cables.)
After charging each cell for about fifteen minutes I took voltage measures with the multimeter and I was able to read 3.6v on both of them. It is encouraging results showing that battery itself is still able to hold charge.
After putting back plate on, came time to test if my jury rigged solution worked. With Power+Volume Down combination I was able to boot into recovery mode.
It worked! Nexus 7 booted into recovery mode.
There are further issues with this particular Google Nexus 7 tablet, as it depleted it’s battery during system update, but for now I am happy with it booting to recovery mode. Presented procedure should work for any Nexus 7 that won’t charge due to depleted battery.
Thank you for reading, I’m looking forward to your comments.