did you read the manuals? desktops and all in ones :: thinkcentre m series desktops :: thinkcentre m73 Lenovo PC Support - Lenovo Support DE

can you enter the bios? check all cables if there are all connect correctly

i guess you should watch out on second-hand market however, maybe its possible to solder?

SOLVED: How to run iPad without battery? - iPad 3G - iFixit "arbaman @arbaman POSTED: DEC 6, 2018 OPTIONS iPad is designed to run with a battery, thus there’s no really easy solution for your need. Not sure if the system requires also a battery presence acknowledgement or it’s sufficient a component bridging, but unless you’re able to microsolder and have the necessary tools is not a very handy solution. If you have to find and pay someone doing the job you’d end up paying multiple batteries cost to get the job done. All in all I believe a battery replacement is the easiest and cheapest solution."

open it and disconnect the battery cable, then push the power button for 30 sec, after that reassembly the device. please give feedback