uboot ignores input

[cwalls]

Hello,

I am connected to the serial pins at the back of my Kindle Voyage (5.13.5).
The connection seems to work fine, when I press a key at the right time, I get dropped to the 'uboot >' prompt.

However all further input gets ignored. If I press enter the cursor just goes to the beginning of the current line, no matter what I typed.

I also noticed that if I connect to power (via usb) lots of gibberish appears on the serial terminal.

Another Issue which might be related is that if I try to boot normally, I get stuck with:

imx_epdc_fb imx_epdc_fb: unable to set VCOM = 250mV (err = -22)
..
BATTERY INVALID: -22
..
=== BATTERY ID IS INVALID. STOPPING BOOT ===

I am grateful for any Infos/Ideas!

[eddie.t.h]

Everything indicates damage to the battery. To be sure, check its connector, preferably under a microscope.

[cwalls]

Is it likely that this (bad battery) is also the cause for the uboot problem (uboot prompt ignoring any input)?

Yesterday I was able to temporarily make it boot normally. But iirc uboot shell was still unusable as described. I then unplugged some wires, because I again wanted to look at the back of the motherbaord. After that, the battery issue reappeared.

What is imx_epdc_fb? Maybe the line

imx_epdc_fb imx_epdc_fb: unable to set VCOM = 250mV (err = -22)

is caused by not having connected the e-ink display correctly?

In the following image, is it correct that the chip/connector at the top left (J1603) is for the e-ink display, and the one at the top right (REV02 written on it) is for the touch sensor?
https://www.mobileread.com/forums/at...2&d=1415313934

In an attempt to remove the battery I used some force, which bend the battery a little. Can such bending cause such battery problems?

I already have checked the connector before, however I don't have a microscope. Sorry if this is a bad question, but what would I look for anyways? Just bend pins and dirt/dust?

[katadelos]

Originally Posted by cwalls

Is it likely that this (bad battery) is also the cause for the uboot problem (uboot prompt ignoring any input)?

Possibly, could also be a bad connection to the serial port too.

Originally Posted by cwalls

What is imx_epdc_fb? Maybe the line

imx_epdc_fb imx_epdc_fb: unable to set VCOM = 250mV (err = -22)

is caused by not having connected the e-ink display correctly?

That line is an error from the driver for the display (IMX E-Paper Display Controller FrameBuffer). Leaving the display disconnected will cause that error.

Originally Posted by cwalls

In the following image, is it correct that the chip/connector at the top left (J1603) is for the e-ink display, and the one at the top right (REV02 written on it) is for the touch sensor?
https://www.mobileread.com/forums/at...2&d=1415313934

That is correct.

Originally Posted by cwalls

In an attempt to remove the battery I used some force, which bend the battery a little. Can such bending cause such battery problems?

For sure, I'd replace it.

[eddie.t.h]

The battery error is caused by one of the connector pins being out of contact from the thermistor built into the battery. So I would look for anything that this lack of connection could be causing. Of course, it is possible that the damage is inside the battery.
What voltage do you have the ttl converter for? Check that you have a good ground connection.
The board will not boot up without the display plugged in.

[cwalls]

I was able to solve my problems:

The "uboot ignores input" problem as well as the problem of gibberish appearing while usb is connected were caused by not connecting with ground correctly.

The battery issue went away after I plugged in the e-ink Display correctly.

Thank you