Mamba max (not pro) and 4s

[mwe-maxxowner]

I have read the mamba max is 4s capable with an external bec. I have installed an external bec and clipped the red wire on the receiver plug just like I should. When I plug in 4s it won't do anything. I'm sure it's sensing over voltage and protecting itself. Can this be overridden without a computer engineering degree?

3s is fine on most of my brushless motors, but this is on a 3.3 revo/emaxx tranny/titan 550 based crawling truck, and the titan 550s need a little more than 3s voltage.