Apparently the best j runner update sometime this month will fix thisBits of advice before I forget:
For me J-runner wouldn't flash the RGH_Trinity.bin says it wasn't a ECC file, so I had to go into "Advanced>Custom Nand/Timing File Functions" Then select.. Command "Write" Size "16" then "Run" it says write failed for all blocks but Xell still booted and displayed my CPU Key (saw this tip on Reddit)
Don't boot Xbox with Nand Flasher still attached (I not 100% sure it's necessary, but I wouldn't do it
everything else is in the Readme..
It will also auto convert to rgh 3 timings so you don’t need to use the python script or GUI tool