Starting without taking off cmos battery.
Installing adapter for long can short the motherboard.
Installing and uninstaling ic when adapter plug in.
Measuring voltages on motherboard with blunt probe.
Removing super io (winbond, ite, smc, via, nuvoton, etc) without removing bios ic.
Reflowing / soldering on one point without temprature control.
Removing ics repeatedly can damage the chip due to overheating.
Plug in adapter without checking the electrical material conductor stick in motherboard.
Testing motherboard without heatsink and fan.
Heating chipset above 180 degree celsius.
Removing ic forcefully