3 days in, slow/stuck or no boot.

[lgmpbp2]

Yes the emmc switch, on is....  disable= on = emmc off ,, This is indeed backwards to normal understanding
occasionally the sd sodket or board is bad, at a guess 1 per 10K
Is it possible that the SPI did not get completely erased?
Maybe I misunderstand, I thought you said the voltage select problem was for emmc
with a pmOS usb boot, but now you say pmOS worked on emmc?
To erase uboot, just write /dev/zero to 1st 16M, maybe save mbr first if it would be usefull, as so
dd if=/dev/zero of=/dev/something bs=1M count=16    ..... all this as root,,,, to install image (most are .xz)
xzcat image |dd of=/dev/something bs=1M    ....but VERY sure that you have right output file, of=
SPI is different, idbloader starts at 0 rather than 64 sectors as on sd, emmc

Thanks for the response, @wdt 
Thanks for clarification of the backwards emmc switch's on and off. That is helpful.
Voltage select message seemed to occur with not only pmOS but also Armbian as I recall. Nothing would really boot up and would receive the voltage select message.On Tow-boot, voltage select message occurred with emmc, sd, usb. pmOS would boot up from usb, eventually, but it would boot up without going through Tow-boot or that is how it seemed to work.
To be clear,the usb emmc module adapter seemed to flash the pmOS software well enough on my other laptop. But emmc modules don't seem to work on PBP.
Thank you for the erase u-boot formula. I believe this has been a u-boot problem, or at least most of it, and perhaps the timing is off somewhere. I don't know if SPI flash is completely erased but it certainly seems that way since I cannot even  put Tow-boot on, again.
Would it be possible for someone to put the solution to the Manjaro u-boot issue on here somewhere?
I really don't know what else to do. It has been said that totally bricking the PBP isn't possible and I hope so and hope that I could eventually get this going, somehow. Thanks again.