I have a old RB532 with OS 3.30.
Since short it is not reachable. The left upper green led is blinking aprox every 3 seconds.
Holding the reset button does not change the situation
Is the router dead or can I bring it back to life

Wilmar

It's time, after 16 years, to change the router.....

It's time, after 16 years, to change the router.....

Done already more then ten years ago and again three years ago.
But just curiosity: What can be wrong.

You can netinstall it with latest 5.x supported version, after free upgrading the licence format from 3 to 4 digits.
But I do not remember the number of latest 5.x supported versions...

But just curiosity: What can be wrong.

Power supply components problems come in my mind. Either external power brick (which might show correct voltage while not loaded but can't provide it when loaded) or some internal power components, like dried or otherwise damaged capacitors.

First of all connect the console to know what's going on. It may be bootlooping for various reasons (corrupted nand, bad caps, ...).
On these older boards bad caps were common problem, for a quick check you can solder some new caps in parallel to the old ones and see if that helps (much faster than replacing them all). If it changes anything, replace all electrolytic caps. But always fix hardware issues first before trying to repair the software (netinstall), because otherwise you are risking NAND damage if power supply is not good enough during flashing...
As for ROS version, last supported is 6.33.3. RB532 is not very fast, but as long as you just do bridging or basic stuff it may still be good enough for something...