I turned on my PC after a very long time (3+ yrs). Its a Lenovo thinkcentre M58 and as the title says it doesnt wants to turn off normally. On shutdown, it beeps in the abovementioned order and then the fan keeps running forever. There is no HDD activity and no display output. I have to turn it off by turning off the power supply. I suspected that the cmos battery might have discharged because the bios kept resetting however this issue has still persisted after battery replacement. Any and all help will be appreciated!