If you still get boot failed: You may have an unsupported game encryption. Check the . Some games require a "License Fix" (a specific config toggle).
This specifically affects digital (.pkg) games that require a license.
Instead of using sketchy websites, use NoPayStation (for PSN) or PSN Stuff for high-quality, pre-decrypted dumps. These almost never cause boot failures due to corruption.
This is rare, but possible. RPCS3 requires a CPU with instructions (Intel Haswell or newer) or high-end Zen 3/4 AMD. If your CPU is older than 2013, the emulator may fail to translate PPU/SPU threads fast enough, triggering a watchdog timeout (Boot Failed).