Technical Info:
In the slim boot chain the 2nd bootloader (CB) is split into two pieces. The first part simply starts encryption and loads the second part, which does fuse checks and all the things that the old single CB did. By glitching the first part (CBA), we take control of the system before the fuse checks occur and can patch them out. The slim bootchain has always used this layout and some groups have even tried bringing the slim CBA to phat and using the old single phat (RGH1) CB as CBB. Glitching this way will work if you set it up right, but there are actually phat xboxes that already have their own split CB boot chain which were mostly ones that had been refurbished (CB 5772, 6752, 4577).
What we have done is simultaneously find glitch timings for these refurbs, dump their cpu_key, decrypt the boot chain, and port it to run on every other phat! This means that on phats we can now glitch before the fuse check and thus have an unpatchable hack just like trinity!