U2410, loud beep sound (overheating?)

Hi,

My U2410 monitor was working fine for a couple of years. It spent about a year in storage, in the original box.

Now when I try to use it, it gives a loud beep sound during startup (until the picture shows) and that beep sound will come back at a later time, after varying delay. Once it has started, the only way to get stop it is to switch off the monitor. I'm wondering if maybe there is a problem with the cooling and the beep is to warn me that it is overheating?

No external factors have changed since before it was on storage - I still connect it with HDMI to the same Sony Laptop.

What actions can I take to solve this issue?

Thanks in advance for any advice