|In addition to the above very good advice:|
Whenever you reset your CMOS by jumper or by removing the battery, you then need to reenter your BIOS set up and first reset defaults (or if available, reset to optimal settings) and then go back and fine tune those settings to run your system properly. These might include SATA settings to ACHI mode, PCIe video mode, boot order, hard drive selection, memory settings, CPU settings, power settings, and more. This, your tech friend should have done and showed you when her reset it the first time. I am not sure why he felt it necessary to flash the BIOS for this since it would have been an unnecessary risk. He sounds like a good friend, but not as good a tech.
Also run Memtest86 from a bootable CD the same way to test your memory for problems.
Install HWMonitor to check what your temperatures are now to make sure that he did not disturb the CPU's heat sink and to be sure that it does not need to be reset properly.
You have to be a little bit crazy to keep you from going insane.