You don't need another dump, use the dump you took before you downgraded. It's because you haven't got the lv1 patches (that bypass the check to see if you're on the right FW) you're bricked, the PS3's bricking because those lv1 checks are failing.
What I'd do is: flash back the original dump (3.7x) and start over.
1x Slim 2K REX | 1x Slim 2K CFW | 2x CECHG CFW | 1x CECHJ REX | 2x CECHC CEX2DEX
1x Jasper 256 SMC+ROL+Halo case | 2x Jasper 16 RGH | 1x XD mod Slim RGH Matte+Chrome+ROL RGLoader/Freeboot/Retail | 1x Banned Slim RGH+ROL