S2417DG, no longer powers on

Hi,

My S2417DG (revision A00, manufactured January 2017) appears to be dead. I purchased this back in September 2017 when living in Denmark. Moved back to the UK a few months ago and put it away (after testing it still works) for later use when I get around to building a new computer. Finally built a new machine and used the monitor for a few hours without issue until I noticed the refresh rate was set to 60hz. After raising the refresh rate from 60 up to 144 (in the nvidia control panel) the display suddenly deteriorated (it's hard to explain but the display looked like a double negative in color, was very bright and there was a white line down part of the screen, text was near impossible to read like this too)... I restarted my computer at first thinking my gpu was at fault but the issue was persistent through the post sequence and windows boot so I unplugged the monitor's power hoping it was just a crash in the monitors image processor... the monitor wouldn't turn back on, all I get is the white light on the power button and if I push the power button it turns off but won't turn back on again (the light.)
I've cycled the power, unplugged everything, waited a few minutes, held the power button in for ages when bother off and on, tried holding buttons 1 and 4 for a "diagnostic mode"... tried connecting via display port and hdmi, tried using it as an extended display with my laptop (only have hdmi on this) but still, no display. windows does detect and identify the display but doesn't appear to report any problems, no amount of resolution/refresh rate changing makes any difference.

Wondering what my options are, if any? would appreciate some help.

thanks.