Power cuts off seconds after I turn it on

If it's related to power, it is either the power supply, battery, or your charging cable.

To test if your battery & cable is working, you should let it charge. If it has a light on to show it's charging, that means your charger is working. If that light changes colour (I don't know if this model has that) to show that it is fully charged, then your battery's capacity is likely fine.

Beyond that, you might have to open it up and check your internal power supply and components.

One last option might be to take out the ram, give the pins/ends of the ram sticks a gentle clean (no liquids, just give them a wipe with something dry), and stick them back in.