Bios password removal

Has anyone had any luck RESETING the bios password on an acer travelmate 5520….I”Have tried several tricks the worked for me in the pass.backdoor password,buffer overload.Last thing i tried was disassebling the unit for removing the rtc battery on the motherboard for one hour with no luck…WICH WAS NOT EASY SINCE ACER DOES NOT have service manual downloads..