I presume you are using the same power source and the same cable, and that you verified that both are in working order. This is the most frequent reason why devices stop working.
You mentioned rebuilding your remote. Please verify that the correct IR code is mapped to the "0" (zero) key on your remote. Also, the PS3IR-PRO has to be the active device on your remote when pairing the PRO with the PS3.
I also presume the PS3 was in pairing mode when trying to pair the PS3 with it.
Can we interest you in an upgrade to the world-famous PS3IR-1000 for $39.95?
Has anything changed in your setup that would cause the PRO to expire prematurely?
Last but not least, fear not for we still have a couple of PROs in stock, for just such cases.