One of the nice things about AMD CPU's is that their socket-type doesn't change half as often as Intel's and is often back-compatible. Phenom 2 uses AM3 which will also work in AM3+ socket motherboards (AM3+ have support for 8-core chipes).

So, given the above, I would opt to get a really good AM3+ board for future-proofing purposes. Your current Phenom II will still work (if it works at all) with it. If bootup is still a no-go after installing the board, there's no need to return the board or uninstall it, just purchase whatever chip you want, it should be compatible.