Blazer_USB works with UPS but not when I try to switch to NutDrv_QX: Driver failed to start (exit status=1) about nut HOT 1 OPEN

The first part says Error: Section aeg not found in ups.conf and indeed I do not see an [aeg] in the ups.conf excerpt (or is it the full file content - then certainly missing that bit?) Drivers would check that their name matches the driver in the section, so that would be another point for them to complain about mismatches, BTW (usbhid-ups vs. blazer_usb or nutdrv_qx).

Note that for testing you can start driver programs directly with -s arbitraryUpsName and ALL options specified as a series of -x key=value.

FWIW, later "screenshots" indicate a configured section named megatec. And as far as that trail says, you start that one (/run/nut/blazer_usb-megatec.pid) and then try to start with nutdrv_qx. The port is occupied by the blazer driver which you did not indicate stopping, so nutdrv_qx can not use it (termination of the other instance pertains to same-driver fratricide, as a workaround for processes stuck in I/O, etc.).

Not sure what your OS is, but it may be that systemd keeps the driver instance alive (which would also conflict with services you start manually); the nut-driver-enumerator family of services can create nut-driver@name instances based on ups.conf sections (see https://github.com/networkupstools/nut/wiki/nut%E2%80%90driver%E2%80%90enumerator-(NDE) in Wiki).

Potentially, bus, device and busport options can also be troublesome as they depend on OS device (re-)enumeration which can change over time. Try commenting those away too.

from nut.