Security check bounced ... I screwed up!

[George P.]

Hey BP,

So like the title says, I screwed up!
Okay, story time.

I rented my place to three tenants that met each other online. I did a background and credit check on all of them and it looked good.

I requested a cashier's check or cash for the first month's rent / security deposit due at the signing. Two of the tenants had a cashier's check and one brought a personal check. 

The person with the check noted the reason for the check and not a money order was that they were a little short this month due to the double rent payment (their current place plus my apartment). They asked that I cash this check in a week's time so that they can get paid first. 

I gave them the benefit of the doubt (mistake) and agreed. The check bounced.

The move-in date is tomorrow and they haven't moved in yet.
Now, I would like to think it was an honest mistake and everything will be resolved but I have contacted the tenant and they haven't reached back out to me (granted its only been 7 hours).

What are my options here?
Can I prevent them from moving in at this point unless a payment is presented?

Thank you!

PS.  The tenant reached out to me two days ago asking me if their check has cleared. My bank account showed a credit for the check's amount so I said that 'it looks like it did'. The day after, my bank recorded it as a bounced check.