There are lots of fakes out there but also the ones that you say are corrupt are fine. But unfortunately no CFW will work on your PS3.I would love to jailbreak my Ps3 Super Slim 4.81 OFW but all of them are fakes or corrupt!
To install CFW your console would need to be able to be downgraded to 3.56 or lower, superslims cannot be downgraded at all.