Monitor and PC not communicating

I recently got locked out of an old PC; took it to a local tech, and they bypassed PIN for me. Bought a new computer; it connects to old monitor just fine. I only have the one monitor, so I want to reconnect it to old PC to get data files onto a flash drive. I plugged in theHDMI cable, and the monitor is scanning for input, but won’t display the opening screen.

I’ve tried both HDM slots, made sure all connections are tight, and restarted both PC and monitor several times.

Any suggestions? The local tech is on winter break, or I’d ask them.

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