EFI flash process question

I have a 2011 MBP 15" 2ghz i7, my clip and raspberry Pi ready to go, do I leave the magsafe port connected to power or the battery connected when reading/flashing the chip?

When you flash a icloud locked machine, am guessing changing the serial # is helpful as well? If so, do you just makeup a new #? Or put in one from a dead board of a similar model?

Is there a 2011 2. i7 EFI cleaned/available on here?

For the older models I never needed a MagSafe connected when reading/writing with a pi.
It's not essential to change the serial but this can be linked to stuff like Apples Device Enrollment Program which will ask to load profiles set by the original company/owner (I've only seen one instance of this and changing the serial defeats the DEP profiles).
Serial numbers are in three parts if I remember rightly, I think one relates to model, one to spec set and one part as unique serial for the machine. Changing the (again can't remember 100% but I think it's 4 digits for the actual unique serial part) is enough to change it and you keep the the model info and spec info.
Googling the serial info will clarify if I've remember that correctly and use a Mac serial lookup site to check serial you want to use it for the same machine

i'm not convinced about changing the serial. i did some extensive iCloud testing, and changing the serial doesn't affect the lock status or the find-my-mac status.
i have locked a MacBook i have and changed the serial, and find my mac still locates it.

i have changed the serial on a mba with DEP, and the DEP prompt still occurred.

i'm only changing the serial in the EFI dump, and that doesn't seem to be enough.

if you change your serial then run AHD or AHT, it says "serial unknown" which leads me to believe the serial is stored elsewhere as well, and that one seems to be of greater importance to OS X than the EFI instance.

i'm sure there's one in the repo, i also have an early 2011 2.0ghz i7 mbp15 in my hands right now.
you should read and clean your own dump though, it's more reliable.

you may have to experiment with power states, but when you get it sorted out, please post your results on the sticky topic i made.

let us know how you get on