Coaster brake bike pedals don't turn

[kjw]

Newbie here, so forgive me if I picked the wrong area for my problem.

Kids 16", single speed, coaster bike. Got for Christmas from Wal-mart b/c he LOVES Superman. http://www.walmart.com/ip/16-Huffy-DC-Superman-Boys-Bike/27831881
Worked fine until today! I didn't believe my son at first since he's a little small for the bike. Pedals no longer turn or turn with great difficulty. I can barely move them by hand forward or backward. At first it would work backwards.

Would too tight of a chain (e.g., back wheel may have slipped though I can't see that it has & the chain does have some play in it) have this symptom?

Maybe a crank bearing has already broke/misaligned/come out, etc?

Thanks in advance for your advice!

--kjw

[Painkiller]

Best thing to do is take back to Walmart and see about repair or replacement, sooner the better. They would take care of it in most cases