Z axis homing jams nozzle into heating bed

My dad got an anycubic kobra 3 v2 combo for christmas, it's been printing well until the original nozzle got jammed, not exactly sure what happened there. Anyway, he used the opportunity to replace the nozzle completely and installed a new ceramic tip nozzle. I believe ever since then he's had this z axis problem. Whenever he tries to auto level the nozzle gets pushed so far into the heating bed that it bends slightly, at which point he shuts the printer off so it doesn't get damaged as we don't have a replacement bed. We've opened and checked the nozzle to see if there's something wrong with the sensor, we've looked everywhere for a solution online, but we've found nothing so far. We tried changing the offset on the z axis but that requires it to be homed first and that would damage the bed. Does anyone have an idea what we could still do? I've seen videos where people have the same problem but I've never found a solution anywhere. He's been so excited about his printer, I just want him to be able to use it again.