[stranger_st]

Hi havhill thank you very much for advice. I did change baud to 115200 and 8N1. It is connected, but In my case (Kindle dxg) connection was different than in ebs version.
1. 5V from converter (where 1 on the board)
2. Rx port.
3. Tx port.
4. Ground.

Kindle has 3 choices while boot.
1. If pressed home Reset mode where you can copy the files to memory where nothing I can see.
2. If press enter you will have Developers choices:

3. Load MMC0 over USB storage
4. Erase MMC0
I. Initialize Partition Table (fdisk) and format FAT
O. Format and overwrite FAT partition
E. Export FAT partition
U. Update using update*.bin file on FAT partition
M. Update using update*.bin file on FAT partition of second MMC port
D. dmesg / kernel printk ring buffer.
Q. quit

And uboot.
In my case the framework is not starting.
I am beginner in linux and I think did very bad mistake.
When I changed browser configs I used mntroot r command I don't know why. than turned debug off and restarted. after that kindle never started normally.

Can I make mntroot rw command in uboot???
How can I fix please help or at least advise. Can I reinstall firmware?
Thank you very much.