[Android Q&A, Help & Troubleshooting] lee_stow:
uart tutorial for cmx box

If u have a cmx box that Is a v1.1 board then this should work for u if u have installed wrong firmware and bricked ur device. Such as red light and no video. This and so works If u r trying to Install ember but ur box will not let ur and gives installation aborted error.

Make bootable sd card with this script in linux. If using windows. Just extract zip rename CMX _ BOOTLOADER. Img to .bin file. Then run bootable sd card tool using file. Then copy cmx_fix_aml_autoscript and CMX _ BOOTLOADER.bin file to card. Rename bootloader file to bootloader.img and rename cmx_fix_aml_autoscript to aml_autoscript. Then short pins with sd card in box. The light will stay red for a while. After 2 or 3 minutes light should turn blue and flash bootloader. I also suggest downloading Ember for cmx box and extracting it onto root of sd card. Just make sure NOT to overwrite aml_autoscript. I definitely suggest using linux to run script. It will download and install ember firmware automatically. Make sure to choose yes when It ask u if u installed g18ref firmware. In terminal. Type sudo su. Then type cd (directory extracted to). Then type ./MakeRecoverySD

If above post did not fix ur problem we must try something a little more involved but almost guaranteed to work.

ONLY TRY IF U FEEL COMFORTABLE WITH A SOLDERING IRON!!! I AM NOT RESPONSIBLE IF UR TURN UR BOX INTO A STEAMING PILE OF SLAG!!!

Okay. Now u must hook up UART module. Make sure to buy one based on the cp2102 chip set. Just search "uart cp2102". U can buy one off eBay for about $8. U can get them for $2-$3 if u buy from china but shipping will take take a month or so.*

FYI : If u have and Arduino lying around, u can use it as a uart module.

Once u have module u will need to solder pin header onto board where the uart Interface Is located (BOTTOM LEFT OF PIC). Then connect RX from uart to TX on board. Then TX from uart to RX on board. Then connect ground from uart to ground on board (the one In between RX and TX on board). Last pin will not be used. Then u hook usb end into computer and install cp2102 drivers from the Web. Just Google it. Take note of which com port it installs to. Now download putty and open it. Select serial connection. Default will be Com1. I had to change mine to Com10 since that is the com port my drivers were installed on.. Then change baud rate to 115200. Put in Bootable SD card made earlier. Then short spi pins (top of pic) while Inserting power. U should see all kinds of info appear on ur putty screen on pc if u connected everything properly. If it's just garbage then check ur connections. If all goes well, then hit enter a few times on ur keyboard after shorting spi pins and powering up. U must do this fairly quickly after started the boot process. This sends a command through uart Interface to the processor to stop boot process. U should now have a terminal to send commands directly to board. Send these commands in this order exactly:

mmcinfo

nand rom_protect off

nand erase whole

fatload mmc 0 82000000 bootloader.img

sf probe 2

sf erase 0 400000

(this will take a while)

sf write 82000000 0 80000

reset

(this will restart uboot so tap enter again to interrupt)

defenv

saveenv

reset

Remember that erasing the spi can take up to 2 mins. so be patient when using these commands.

After this just power off and attempt to flash as per the usual method using the recovery button. (with the uart plugged in you should be able to see what is happening.

This process brought my CMX back to life. Until this I was ready to throw in trash heap. Any questions just drop me a line. ill try and help.

This process was made possible by Josh.5 over at Ember. Could not have done it without him. He is the brains. I am simply regurgitating his genius.