Virtual Boy halts at warning screen.

Hello, I recently got my 2 VB units out of storage to begin testing and playing my games in preperation for selling. Unfortunately I have tried Jack Bros, Red Alarm, Nester’s FunkyBowling, Galactic Pinball, VL Baseball, Teleroboxer, Mario Clash, Wario Land, Marios Tennis and got absolutely nothing different on both systems, I tried them all just to verify it wasn’t the carts. Both systems do the same thing. Does anyone know what the problem is that causes this? Could it be a loose solder on the motherboard or somekind of chip related issue cause by the consoles being in a hot environment or maybe even moving related loosening something up?

I have seen this problem in the past with other units I used to replace bad parts but 10 years ago no one knew what caused this. If anyone can help at least point me in the right direction I would greatly appreciate it.

Thank you very much for reading this.