Just installed a new MX500 after cloning my old drive to it.
Everything appeared to be going well. PC was running fine, I checked a few programs to mak sure everything was OK. Then I installed Storage Executive as recommended. Clicked on the button to update the firmware. PC rebooted into the terminal screen and everything looked like it was going fine. It said it was installing firmware and I had for rows of full stops (periods) and then I got a message which included the Checksum failed error.
I may have panicked (and I did panic) a little too quickly. I put my old drive back in and rebooted. Installed Storage Executive on that and hooked up the SSD via USB. SE reported that the firmware was up to date and OK. I reinstalled the SSD and the PC booted up fine. No idea if the checksum error was real or not. Everything appears fine now.