Older boot with newer [larger] fw_all is not the optimum. Later fw for both units is V4.00. I've remade the hybrid fw using V4.00 and tested it on an NA 40, works fine as a 42. Also flashed it to HWID 1613 with full 42 fw, no problems there either. Here's the hybrid pack in a rar file, extract to find 135001000400.rgn and updater.exe:
Spoiler: Download
https://1fichier.com/?4k80lpno9e


Remove any gupdate.gcd if present in .System folder and flash either full 42 firmware or preferably the hybrid fw to maintain HWID 1350. Please clear nonvol rather than hard reset both before and after flashing.