You can't upgrade soldered RAM, even with a broken slot.

No. Soldered RAM is physically attached to the motherboard — you cannot just swap it out like a stick. The broken slot only makes it worse: you’re now stuck with whatever soldered RAM came with the laptop, and you have one less usable slot.

If you’re hoping to replace the soldered RAM chips themselves with higher capacity ones, that requires a BGA rework station and precise microsoldering. Not a DIY project. Most repair shops won’t touch it because the risk of ruining the motherboard is high and the cost is usually more than the laptop is worth.

Forget “upgrading.” Your best bet is to use the remaining slot if it works, or accept the laptop as-is. If you need more RAM, it’s time to look at a different laptop.