labtop shows power light and turns off

It's usually caused by CMOS RAM corruption. 90% of the time, this can be fixed by disconnecting the pigtail battery and primary from the motherboard, holding it down for ~30 seconds and then plugging both back in.

That said, without a model we can't locate a SM - but I can tell you it's usually next to the primary battery on the modern HP laptops:

NOTE: Some of the newer ones (Notably the Core Ultra/Ryzen 7000) series did away with the dedicated battery or hid it under the primary battery. If you see that connector, you have one. If not it's backed by the primary battery. It's probably to avoid putting a sticker on there about the coin cell despite it being in there where you need geuine malicious intent to eat it because you need to take the laptop apart to get to it.