So i am not quite sure which lightsaber i got from my grab bag. I belive it is an Acrchon

There is a problem with the battery. I try to turn it on and of but it doesn't work. But if I tap it on the lower part af the hilt (where I assume the batteries are) if flashes. I think a battery fell slightly loose but I don't know how to take the batteries out. If someone could tell me how to remove the battery so I can to try to fix it or link me a video that could help me that would be great. I look forward to seeing my beautiful Guardian Blue light once more.