Sounds like your 1st development was off and/or the peroxide (bleach) bath didn't remove the developed silver from the developed negative image, either because the dilution was off or the time was off. The fact that you can see some vestige of image points to the bleach step being the culprit.
The bleach step gets rid of the negative silver image, and the re-exposure and 2nd development affects only the silver halide which is left after the bleach step. If you leave the bleach step out, the second exposure will overexpose (blacken) the entire film strip.
Here's a guy that's doing it in a similar way. He has times and temperatures for each step.