Touch screen USB connection, causes RPi4 B, not to boot

ARGON ONE (V2 and M.2) DISCUSSION
1

I have been using the Argon One M.2 case for almost a year. I was having low battery indications on screen. I am using a 12v to 5v converter in my boat to run the RPi4 B 4G. I am using a NewHaven 7" Display with touch screen. It was plugged into the same converter for the RPi. Looks to be too much draw, so I seperated them, no more low battery indicator.
Recently attempting to find the issue with low battery, the RPi stopped booting if the USB cord for the touch screen was plugged in. It completely stops the boot process. If I remove the USB cable until the RPi starts to boot then plug it back in, it will complete the boot and everything works fine.
I installed the M.2 drive into a Ugreen case and plug it into the USB port that I removed the bridge from, and the RPi boots without any trouble and the touch screen works great.
So why when the M.2 drive is in the case, it won’t boot properly, but when that M.2 drive is in an external case and plugged into the same usb port, it works fine?

Any help or pointers would be appreciated!

2

After testing many combinations, I believe I have figured it out. With the Argon M.2 and display connected together via HDMI and USB for the touch screen. If they are run off the same 12v power converter, I get low battery indications. But it will boot up and operate properly.
With the same configuration but using two separate 12v Power converters, Both converters need to be turned on at the same time. If not, then the touch screen usb cable needs to be unplugged in order for the RPi to boot.

So I can live with that. Just thought I would pass along what I found in case it helps someone else.
Thanks
Dick