James Hill iCracked Technician

Try this: Won't power on, vibrates every 5 seconds, with replacement battery..

I see a mix of problems. Please help clarify: Was, Randomly turning off Now, will not turn off Now, will not charge Is this correct? Sounds like there are several possible problems. Could be only corrupt OS, or only failing motherboard, or failed charging port with broken power button. It's hard to tell without trial and error to find out what's actually working.

The metal bracket (if I'm thinking of the correct part) is also shielding. Without it, the phone screen shows lines or squares.

Is there any chance of water or dropping damage? Have you tried a DFU reset?

Did the whole phone suffer water damage? Did they also change the battery when they did your repair? Did the repair place conduct water damage repair or just replace the non-functional parts? There may be some corrosion that is (and may continue) causing the malfunctions.

Did you disconnect the battery each time prior to adjusting the connections?