Old iMac does not come back after firmware upgrade

My wife upgraded the firmware on an old Intel iMac. The white light on the monitor is solid, but there is this clicking sound. There is no output on the monitor. It gets stuck with the clicking sound and the same thing happens after doing a few hard reboots.

The computer is on its last legs. I am guessing it is some hardware issue. Should I just save for a new computer or invest the time and money to fix this?

Is there a way I can run a diagnostic to see what's broken?

First, why was it necessary to update the firmware? Apple normally does not release firmware updates for machines that are several years old or older.

The clicking sound is likely the hard drive or possibly the optical drive trying to activate. It's possible your wife applied an incorrect firmware update to the iMac and now it's dead. I really don't know if you can undo the update since you gave us no info regarding your iMac.

The Apple Firmware Restoration CD is for Intel Machines only which your is. Give it a try.