I have the same problem: Just bought a unbranded 7" Notebook of eBay, played with it a couple of hours and when I inserted a SD card it just died.
I am trying to get a refund, but if I can fix it, it would be easier - I am an electrical engineer and develops embedded systems, mostly based on ARM, for a living.
It is based on a AK7802 running 248MHz (is sold as WM8500 300MHz).
The PCB looks exactly like this: [You must be registered and logged in to see this link.]
Some initial observations:
- Charger light works.
- When pressing power button there is 5V on the USB ports.
- It uses apx. 70mA from the battery when pressing the power button.
Some observations after I opened it:
- The RTC oscillator is running.
- All voltages (5V, 3.3V, 2.4V, 1.2V) seems ok when the power button is pressed and the main oscillator is running. When the power button is released only the 2.4V RTC supply is present.
- Something is output on the debug port (CN1)
- The voltage on the SD card detect pin on the SD connector is only 1.0V - it should be close to 3.3V - in comparison the write protect pin is 3.0V.
Unfortunately the card detect pin is directly connected to the AK7802 and might somehow have damaged it, preventing it from working properly.