Yes a hardware fault is always possible with a malfunctioning device and it's looking very likely with this one. Of course when a device will at least turn on we usually go with the assumption that it's not. If it is physical flash damage and the device is out of warranty then it's best just stripped for parts to sell separately. However, the vast majority of devices which boot to the logo screen can be saved because they only have a software fault or a corrupt file or memory region. Seeing you were able to get V5.90 cure firmware to load as an RGN file in preboot but there is still no MSM available is very concerning however. All cure fw does is prevent the firmware from loading any of the usual files IMG, GPI, VPM etc so that a faulty file cannot 'brick' the device and importantly allow MSM again. However because those files aren't loaded the boot sequence freezes at the splash screen as intended. Although cure fw has apparently loaded, your device either turns off or boot-loops rather than proceeding as far into the boot process to stick on the logo splash screen. My feeling is that at least region 14 where fw_all.bin is flashed isn't actually being re-flashed, so it does strongly indicate a hardware problem.

About the screen messages: "Loader" indicates that preboot is engaged and locked in due to initialization with Updater.exe, "Software Loading" indicates that the device is receiving data to its memory regions from Updater.exe. However despite Updater indicating that the data transfer was successful the subsequent device behavior (no MSM and turning off/bootlooping) indicates either it wasn't actually loaded to the device (likely flash memory fault) or there is something else preventing it from booting. That 'something else' should not be a bad file because they aren't even loaded with cure fw onboard. Regardless i don't think it's even getting as far as trying to load files before the boot process ends which explains why cure fw makes no difference.

So, summing up from the info you've given:
This device cannot read from microSD card so we can't use Update.txt commands to flash BIN file to regions or erase regions; and
It seemingly accepts V5.90 cure fw however MSM is still not available because booting is interrupted by something very early in the process.

This really does seem like a physical flash failure. If it is 'something else' other than flash damage I have no idea as to what that might be. In some cases with a boot-looping device, leaving it on charge connected to a USB port on a running PC for an extended period of time, like for a day or more, might eventually "fluke" a complete enough boot to enable MSM giving access to the internal filing system. I don't know if that will happen with your device but if it does you would be able to take a backup of it's files and reformat using RMPrepUSB. If it's not a corrupt file causing the problem which I strong suspect it's not, then that won't achieve anything anyway.

Maybe someone else has some other thoughts or suggestions to contribute.