Chuwi Hi10 pro won't boot

Windows Tablets Hi10 Pro
1

Model: CWI529
S/N: PQ64G42161101925
BIOS chip: W25Q64FW

Hello everyone,
Sorry for my terrible english.
A few years ago I took the opportunity to buy a Chuwi Hi10 Pro with its keyboard. Except for one well-known problem, I haven’t had any major problemes that with the microSD card reader.
But last year I left the tablet off for a long period of time with the keyboard connected. When I wanted to use it again there was no way to get it to boot.
Reading around here on the forum and in the Telegram groups I tried all the combinations I could find to try to revive it: holding down the power button for 30 seconds, holding down “power + vol-”, “power + vol+”, “power +vol- + vol+) at the same time…
None of them worked for me.
I then thought that possibly the battery was so discharged that it wouldn’t activate the BMS to allow charging the batt.
I took the tablet apart, disconnected the battery and, indeed, the battery was well below 2.5V. Using a radio-controlled LiPo battery charger, I tried to run several charge/discharge tests to check its status. The battery had lost some of its capacity but was barely 10% damaged.
I charged the battery in the charger, connected it to the tablet and still couldn’t get it to start.
Reading many threads, I discovered that leaving the tablet with the keyboard connected caused the battery to discharge since the keyboard had a small consumption.
I also have a device to check the status of the chargers of my devices and I found that when connecting the tablet to the charger, a consumption of 1 or 1.2 Ah was observed. I couldn’t get the tablet to start, but, however, I could see that in the area under the heatsink covers the CPU, the temperature is noticeably increasing.
I also read on the forum that it could be a corrupted BIOS, so I looked for the correct one to try to flash directly on the Winbond chip, but when I connected the clamp to read and write the flash, the CH341A programmer disconnected from the PC and stopped appearing in the Windows 11 device manager.
I unsoldered the chip from its board and once it was off it was possible to read it (to make a backup) and write it (to write a clean BIOS). I soldered the chip again, checking carefully that there were no shorted pins, but the result was the same as on previous occasions.
Doing more tests, I tried connecting the tablet directly to my laboratory power supply, selecting 4V and a maximum of 2Ah of current.
I see that as soon as I powered up the tablet had a consumption of more than 1Ah and that if you held down the Power button for 5 seconds, its consumption dropped to about 400 mAh.
I performed the same test with the BIOS soldered to the tablet and with the tablet without its BIOS.
I don’t know what further tests to perform or I should give up on the tablet and try to use its components for other projects.
Any guidance and/or help would be appreciated.

2

At this point considering everything you have done, the only thing i could recommend is to send to repair, but i dont think would have warranty anymore. Maybe @manonegra222 has another idea

3

No, tenemos a otraver en el grupo de Telegram y conocemos el problema, sabemos que dejar la tablet apagada largo tiempo con el teclado conectado produce una descarga lenta de la bateria hasta niveles inferiores a los necesarios para poder arrancar pero, ha realizado todo lo posible para intentar recuperarla y ésta no ha arrancado. No se nos ocurre nada que hacer pero repasaré de nuevo lo realizado por si algo más pudiera hacerse.

4

Gracias, @manonegra222 .
Más que nada, he redactado el post por si finalmente consigo recuperarla, que le sirva a alguien más.
Lo cierto es que es más un reto por intentar solucionarlo ya que hace tiempo que he sustituido la Hi10 Pro por otros productos Chuwi (Corebook Pro y Corebook XPro) y por eso la Hi10 Pro estuvo tanto tiempo abandonada.
Cuando tengo tiempo me gusta cacharrear. Ya vés, como comentamos en telegram, la tablet junto a su teclado me costó menos de 200€ hace ya demasiado tiempo (jejej) y sé que aunque la recupere se quedará luego en algún sitio sin determinar hasta que me vuelva a acordar.
Y gracias tambien @ChuwiSpainSupport (María Isabel), pero la garantía ya hace demasiado tiempo que se acabó y enviar a reparar una tablet tan antigua no merece la pena, económicamente hablando. Es más el, como digo, “cacharrear” y reparar algo que no entiendo por qué no funciona.