Solar panel spot light isn't working?

There's a good chance the batteries are worn out, if these things are any age at all.

I had some of these things for a while. The batteries that came with them were junk, cheap Chinese no-name crap with no capacity to speak of. I replaced them with much better NiMH rechargeables (unfortunately also made in China, but what can I do?) with more than double the rated capacity and the light was then both brighter and lasted all the way until morning.

Your spot light may be pulling more amps than the batteries can supply for any length of time. Under heavy current draw the voltage goes below the system's low-voltage cutoff, and *blink* the whole thing turns off.

So try new batteries. As a first guess, it's a relatively cheap solution.

If you have solar panels installed on your roof... switch to grid system. Save yourself on hassle with the batteries and you will never run out from electricity. Your issue might be that you produce less than actually absorbing.