If a Surface Pro 7 won’t power on after sitting unused, it’s usually due to a deep battery discharge or a power delivery issue.
If possible, test with another Surface charger (65W+) or a USB‑C PD charger (45W+). Make sure the Surface charger LED lights up.
Leave it plugged (Without Power On) in for 24–48 hours to recover from deep discharge.
Hold Power + Volume Up for 15–20 seconds, release, wait 10 seconds, then press Power.
Connect via USB‑C/MiniDP to rule out a dead internal screen.
If none of these work, the issue is likely with the battery controller or mainboard. At that point, service through Microsoft Support.