If the Shop don't offer you replacement so open your AP and have serial access to it debrick it using the TFTP.

Thanks

You are right at the point " your ISP is using DFS for a reason".

At http://www.tp-link.com/test/products/details/cat-37_TL-WA7510N.html#specifications there is written that the WA7510N supports frequencies 5.150-5.250GHz 5.250-5.350GHz (Support Dynamic Frequency...

No,the problem of DFS in OpenWRT is that i can't find my ISP AP,because my ISP AP uses the DFS channels.That's why i need the DFS channels in OpenWRT

You are on OpenWRT also.