Yes, it does.
@Scarlett I can also confirm that you don’t need the main battery in order to power on the laptop: it only needs AC plugged in. It would be a waste of money to buy a new battery at this point - it surely can’t be a dead or low battery causing this issue.
I must say, unfortunately, that I am not too optimistic about the way you describe how it happened - that it suddenly went dead and no way to power it back on again. In fact, what you describe has happened to me already once, but I was fortunate to have access to another (working) Librem15/v4 so I could do extensive troubleshooting (swaping boards or other components) - and this resulted in the worst case diagnosis: motherboard toast!
Eventually, I could repair it, because I was able to get the part (whole MBD) from Purism Support, and it was not even so expensive.
But disassembling the entire laptop in order to swap MBDs and putting it back together is NOT an easy thing to do. I think a more reasonable way to go is to get an RMA from Support and ship it back to them for troubleshooting and then give you an estimate.