E6420 corrupted bios problem

Hello all,

I was happy user of E6420 until last week, when the device has stopped to boot. After power up there is a dell logo, progress bar on the bottom of the screen, progress goes to 100%, then all or +-upper half of the screen is going blank - and that is all. No access to bios, no os boot.

After some basic checkings (disc, memory, cmos clear) i gave up and gave my lap to repair. Electronics has said that they reflashed (by desoldering the chip) the bios and the lap was alive again until they booted the windows 10. After this they had to reflash the bios again. They claim that e6420 is not prepared for win 10 and they suggest going back to win 7. This was astonishing for me. Can anybody confirm that? There are normal support for win 10 drivers for e6420 on del www. How win 10 could corrupt the bios?

The other thing is that there are 2 os'es on the HD: win 10 and debian jessie and grub which let the user to choose the os. I was using rather linux than windows the day before the crash. They cannot boot the linux as it is on the encrypted partition.

But they are booting some systems (i do not know what systems) from usb without problems.

Is it possible that this is really win 10 problem? Can this be a virus or something? Can this be grub or linux problem? Is this possible to reflash the corrupted bios on e6420 without desoldering the chip?

Thank you for any suggestions and help.

Best regards,

jb