Why is my iPhone 4s stuck on the apple logo?

Hi.I was using my iphone 4s for music until it reached 18% battery.I left it for the night and the next day I found it dead so I went to charge it.At first It was bootlooping but after leaving it for 2 hours it is stuck on the apple logo.I also put the positive probe of a multimeter to a part of the motherboard and the frame and it beeped.Does that indicate a short?Ive replaced the battery but it's still isn't working.Ive also try hard reseting it but nothing.I want to fix it but I also don't wanna lose any data.Is this possible?Thank you very much