The BIOS and BIOS configuration are stored in non-volatile memory (a Flash memory chip). If you badly configure the BIOS, like I did, you can lock out access to USB and even stop the tablet from booting.
(If you are able to launch Windows it is possible to flash a new BIOS with a Windows utility – search the Chuwi support forum for details.)
If you can’t boot in to Windows then you have to use these flashing tools…
You will need:
- A soldering iron – to disconnect the battery from the circuit board.
- Flash Memory Programmer interface (CH341A with 1.8V adapter and in-circuit clip)
- CH341A Flash Programming software – CH341A Flash Programmer V1.30
- Chuwi Hi8 BIOS image – download the latest from the official Chuwi website or Chuwi Hi8 BIOS 207.
- A Torx #3 screwdriver to open the Hi8 case. (Then use a credit card to unclip the back of the case from the front.)
- A PC to run the flash programmer
Before you program the BIOS you must unsolder the red wire of the battery. Its a good idea to wrap the end in some tape to prevent accidental short circuits.
Lift the metal shield by the edge using a fine blade being careful not to damage any of the very small components. The metal shield is held in place by clips.
Pin 1 of the BIOS chip is not the one marked with green. The PCB has an arrow and the chip has a black spot for pin 1:
The red wire of the in-circuit programming clip connects to pin 1.
After this preparation you then:
- Install programming software
- Connect up the flash programmer
- Connect in-circuit clip to the BIOS chip (Red wire to pin 1)
- Click the programmer detect button to auto-detect the chip
- Make a backup of your chip’s BIOS. Read the BIOS image from the chip and save it to you hard drive.
- (If you cant do step 5 do not continue further!!!)
- Erase the BIOS from the chip
- Load the new BIOS in to the flash programmer
- Write the BIOS to the chip – make sure it verifies correctly. Repeat if necessary.
- Remove the in-circuit programming clip
- Close the metal shield – make sure it is aligned with all the little clips.
- Solder the battery red wire back on to the board.
- Power up the tablet to make sure its working. Power it down.
- Close up the case
Now the BIOS is back to default settings and you should be able to use USB OTG again.