Rat Zapper clean yet still blinking

[jetpower]

With thanks to cncjerry for his 2016 Rat Zapper cleaning advice, I did that to my vintage 2021 RZ Ultra after no rats in two years.  So now it's 2023, and rat signals are showing up on the kitchen floor.  Time to whip out and prime the Rat Zapper for a day or three on the job. 

On power-up, its red light began blinking. The batteries test fine - 1.5V with over an amp each.  Following cncjerry's lead, I opened it up and checked the board - solder joints are clean, albeit with a few hints of possible flux traces or corrosion.  After cleaning it with IPA and a paper towel, vacuuming off errant threads so that everything gleamed, I checked the result.  No change - blink, blink, blink.

The component side looks fine, so I have to conclude that an internal short is likely the culprit.  Time is at a premium, so troubleshooting isn't on the menu.  All direction is appreciated, up to and including last rites for the executioner.

[R-1125F]

It is not that complicated.  See this thread https://www.eevblog.com/forum/beginners/where-can-i-find-circuit-for-electronic-rat-trap/

[jetpower]

Tx; it was faster to summon Amazon for a side-by-side test.  Answer:  4.5v @1.5A doesn't satisfy the new model.  It needs a fresh set to wake up the employee.  Oh well, it's still less effort to clean than the RZ Classic model, which starts up again and again at lower power.