Nova Pro - Stripes on screen after using fast charger

[pochopsp]

Hello everyone, something happened with my Onyx Boox Nova Pro.

I have charged the ebook reader with a Xiaomi Fast Charger which
outputs more voltage than the Boox needs. I can read on the rear of
the Boox that it accepts up to 5 volts / 2 ampere of voltage.

I already charged it with the Xiaomi charger in the past without
problems, but this morning soon after I put it in charge two large
black stripes appeared on screen, and they won't go away. I don't see
any other thing on screen besides these stripes.

Is there anything I can do to fix it?
If so, could you help me? And if it needs a repairement, could you
please tell me how much does it cost?

Here there are pictures to let you see these stripes on screen:
https://ibb.co/qrsVvfr
https://ibb.co/MG5sKkS
https://ibb.co/cD9K9Xb
https://ibb.co/DQcdb9m
https://ibb.co/xD0nWq3

Thank you all for your kindness and availability.

[Renate]

It doesn't look good. Does it react to anything?
When you plug it into a computer is it recognized as anything?
Does a long (30 second) power switch press do anything?

Theoretically, no charger should harm a 5V only device.
OTOH, there is complicated standard and proprietary charger logic that if it got confused could pump 20V into your poor device.

Too high voltage can cascade through a system in unexpected ways.
I was helping someone who accidentally let 3.6V into the 1.8V bus.
None of the 1.8V stuff appreciated it, but it wasn't that bad.
The battery however fed a 12V boost converter that fed the LCD backlight.
That got its reference from the 1.8V so it tried to generate 3.6V / 1.8V * 12V = 24V
The 24V vaporized the backlight.

[pochopsp]

It does not react to anything sadly.

It is not recognized by computer, and a long power switch press does anything.

I managed to open it and get to the motherboard, tried to take off all cables and put them back on after some minutes, but it didn't work.

I am resigned to the fact I have to buy another one, but I would be really happy if I managed to get my files that were on it.

[Renate]

If it's open you definitely want to try the EDL test points to see if there is any life in it.
Please post a good photo.
Do you have a voltmeter? Maybe if you're lucky the battery died/locked out.

[Renate]

Oh! I see photos on that other thread.
1) Check the voltage on the black and red battery leads.
2) Get a good photo of the (possible) UART connector or ROM boot option.

[pochopsp]

here are some pics

https://ibb.co/NY3bgS5
https://ibb.co/sKvRPBx
https://ibb.co/hWvB7gk
https://ibb.co/M5Mdwkw
https://ibb.co/TT6rNGS
https://ibb.co/SJPNBZj
https://ibb.co/Vp3Vyzq
https://ibb.co/7nNS656
https://ibb.co/Ttn38Zp
https://ibb.co/vv0QFJF
https://ibb.co/NprCYJ4

If you need any other photo, let me know

[Renate]

First, check that the battery has voltage, 3.9V or higher.

Yeah, the triple is clearly the UART, labelled TX, RX, Gnd.
Use a voltmeter and see if any of them is around 3V
Do you have a 3.3V USB UART?

I've never used RockChip, but the double contact could be a mode option.
I would not short them directly, get a 1k resistor.

[pochopsp]

Hello. I don't understand nothing of what you said unfortunately. I don't have any knowledge in electronics... What kind of voltmeter would I need? What do you mean by "get a 1k resistor" ?

[Renate]

You need just a basic voltmeter, you can probably borrow one.
Don't use one of the older "mechanical" ones with a needle and scale.
They won't hurt anything, but they load too much to be accurate on modern low-power electronics.
You can buy a DVM for $10. It will be poor quality and bring no joy to your heart but it will do the job.

Once you measure the TX pin vs GND you'll know what logic level you have.
I would guess that it's 3.3V, but it could be 1.8V.
You'll need a USB UART that works at that logic level.
If you want something upscale that works with either level you can buy this:
https://www.amazon.com/DSD-TECH-SH-U...dp/B07WX2DSVB/
Admittedly, adapters that only work on 3.3V can be found for ~$5.

Originally Posted by pochopsp

What do you mean by "get a 1k resistor" ?

Well, you can buy it. You can remove one from some junk electronics.
The value isn't critical, but 1k is a common value, 1000 ohms.
Ask an electronic friend to borrow one, its value is about $0.01
Unfortunately, nobody sells one for $0.01