Your agility is second to none! 
So hereās what I think is going on
- The two stepper drivers are set to deliver 3.3 A each to the motors.
- The Ruida controller requires maybe 1 A for all its functions; this is not documented anywhere I can find
- The power supply is rated for 6 A maximum, but must deliver something over 7 A
This works most of the time, because power supplies can deliver somewhat more than their stated maximum current. Machine designers, at least good ones, donāt abuse that margin and, indeed, specify a slightly larger supply than absolutely required. Obviously, supplies with higher current capacity cost more, so thereās a powerful motivation to use the cheapest supply that doesnāt fail immediately.
In point of fact, my laser has a third stepper driver for the Z axis motor, set to 5.1 A peak, so the ā6 Aā supply must deliver nearly twice its rated current. That the poor thing doesnāt fail continues to amaze me, but, as the old song goes, itās living on reds, vitamin C, and cocaine.
With that long-winded explanation in mind, I think the power supply in your laser is at the other end of the spectrum: it can deliver just a little more current than its specified 6 A, but eventually the overload causes a voltage glitch that trips the stepper driver under-voltage error. When the stepper drivers turn on their red LED they shut the motor off, thus eliminating the overload on the power supply, which promptly resumes normal operation.
If thatās whatās going on, perhaps reducing the motor current will improve things. Reducing it too much will cause other problems, but you can probably get away with a little tweak.
The DIP switches are identified by number, with switches 1 2 3 controlling the current. Right now theyāre set OFF ON OFF which calls for 3.3 A peak.
With the power off, flip switch 1 on both stepper drivers from OFF to ON, so they are ON ON OFF. That will reduce the current to 2.8 A peak, which might be juuuust enough to unload the supply.
Then see what happens during a few runs on a scrap mug ā¦