For some reason I thought you were talking about the first ram slot, not the one labeled 1 lol
I would try reinserting the RAM into the “bad” slot and resetting a few times to see if the error goes away, you can also try a hard reset by disconnecting the power, removing the rtc battery and holding the power button for a few seconds then reinserting the battery and trying it again.
Motherboards have a BIOS flashed to them, if they’re not completely powered off after BIOS flash weird things can happen. Usually you won’t have to do this because standard laptops are shipped “ready to use”, but anytime you’re assembling a computer you can expect weird things like that the first couple boots.
I left the memory in channel 0 and turned on the laptop this morning expecting the same issue but it booted into bios, so I’m not sure what happened last night that caused an issue.