Peculiar HP-41CV with RS 620-480 Logo

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What happens when you turn it on?

One way to try and get control is to press and hold back arrow while turning it on (forcing a memory reset), or press and hold ENTER then ON. Then try some keys and observe what happens. You can also try to remove the battery and do the same.

If you have the ability, try the diagnostic module.

If there are some peripherals attached, remove them.

Håkan