Perfectly clear.
(1) You pay upfront in full.
(2) There is no cancelation charge 30 days out additional to the rate you paid and
(3) the prepayment is non-refundable
Yes, it looks ambiguous at first. But they're simply telling you that more than 30 days out there is no charge to cancel — some hotels charge cancelation fees — but you won't get your money back if you do.
The ambiguous bit is the implication that there is therefore an additional charge (not specified) if you cancel within 30 days of the stay.
I wouldn't touch this hotel with a bargepole — find somewhere else. $249 a night is ridiculous to be surrounded by rowdy football fans for two nights.
sorry but you are not correct, the prepayment is refundable up until the A+30 mark