iPad 6 battery drain while standby

I’ve received and iPad 6 to repair. Turns out not only the glass was broken but the battery was dead and the LCD is cracked.

I’ve replaced the glass and the battery. The iPad turns on and works great. Except for the cracked LCD which I still need to replace.

Before investing in a new LCD I noticed that the battery would drain quite fast.

I’m losing about 2% an hour while standby. Playing a YouTube video will drain the battery from 100% to 0% in about 3 hours.

Notes and things I’ve tried:

• Restore the iPad (I’ve not yet done a DFU restore)
• I’m not signed in to iCloud, iPad is factory reset. There are no apps running, no Find my process.
• Charge to 100%, run it down to 0, charge to 100% and leave it for 4 hours.
• When at 100% and connected to Coconut Battery it says 96% charged. When doing a force restart (home + power) it reboots and jumps from 100% to 96% and goes back to charging for a couple of minutes. Doing this a couple of times will end up with 98% in Coconut Battery and 100% on the iPad.
• Update to iOS 15.6.1
• The iPad get ‘warm’ on the rear when in use. Right around the motherboard battery connector is my guess.

Could the battery be bad or could there be something else wrong with this iPad?

Could the cracked LCD cause the drain?