Lenovo laptop randomly shuts off

Hello,
i've had this problem for a bit of a time now (approximately 5-6 months)
sometimes my lenovo laptop just shuts down. there's no warning and no minidump or entry in the event log either. it's not the power supply, at first i thought it was the new battery i bought but i took it out and it keeps crashing regardless. sometimes it doesn't happen for about a month, sometimes it happens twice in a week. it usually immediately restarts itself after it crashes as well. does anyone know what to do? :(