From ST2205u wiki
On my device (Pixika Digital Photo Frame) holding left+enter while doing reset (at the back of the device) Make the device enter in test mode It displays :
- white, red, green, blue screen
- lines to see defects on screen
- software version
- then it enters in key press mode
=> then left+right make the device swith off, you have to do reset again to switch it on...