If your power actually goes out, even for a few seconds on occasion, a surge protector will not help with an actual outage and will not prevent restarts.
Most computers can withstand a restart and a surge protector will protect against voltage spikes during the stop and start of power. That should work fine.
If you do not wish the restart, or there are many ...
... This has happened with multiple USB-C chargers, though I do not
have a barrel jack charger to test that out.
This appears to be a battery failure.
See if you can do a Battery Reset.
Charge to full charge. This may be problematic based on your description. Get a barrel jack charger if you can.
Once charged, disconnect the charger and and allow the ...
I got an old Lenovo z50-70. It was mostly used with a charger as
previous owner says
If a battery is left at 100% on a charger, it will eventually die. It is doubtful the owner would have known about Battery Threshold charging, indeed the old machine may not even support that.
So at this point, based on your own description, the battery is dead and needs to ...
It won’t be a significant amount, but yes it will consume a small amount of electricity even if the machine is off. The battery slowly loses charge and has to be replenished, some chargers have lights on them that use a small amount of energy, etc.