Prev issue w/ HP Pavilion 754n shutting self off. Blew out dust, added thermal paste to heatsink. Worked about 3 months now shutting off again. Advised to update BIOS, I downloaded, installed & now get System fan error shutting off in 5 seconds. CPU & system temp varies 88-96. CPU fan runs about 1800RPM but system fans shows '0' RPM. How do I fix & can I remove/reverse BIOS update? Removed battery but nothing happened.