OK, I missed the part where you said you already assembled, I thought you were saying you were going to assemble over thanksgiving... Since the parts list is pretty much the same if it was still unassembled you could have gotten a V4.2 board and built that up instead, but I guess that ship has sailed.
So let me try to help you get the 4.1 up and running....
First of all, all the HM versions are pretty much the same besides a few minor changes, as far as I am aware they all support the same firmware, so you should be able to run the latest. The one thing you cannot use on the v4.1 is Voltage mode on the blower, that is just a config setting.
Moving on to troubleshooting, you want to start out by checking the various stages of the power supply. 12V in from PS, then 12v into the OKI DC/DC converter and 5V out, then 5v into the MCP1700-33 voltage regulator and 3.3v out. You want to make sure you have the MCP1700-33 installed in location IC4, note that this voltage regulator looks exactly like the other small transistors on the board so it is easy to mix up, check the printing on the device to make sure you have it right.
If all of your voltages in the power supply are reading right then you should move over to checking the rPi. The HM will be DOA until the rPi boots and flashes the ATMega, you will most likely see black boxes on the LCD until this happens. Speaking of the LCD, did you adjust the contrast pot? If not, do that now, you may just be surprised by the NO PIT PROBE message when you do. If you see black boxes instead that means your ATMega has not been flashed. If that is the case you can plug a monitor into the HDMI on the rPi and see what it is doing, to make sure the rPi is booting all the way. Again, if the rPi is not booting properly the ATMega wont get flashed and the HM wont work.
Here is a link to the v4.1 web pages,
https://github.com/CapnBry/HeaterMeter/wiki/HeaterMeter-4.1-Hardware
https://github.com/CapnBry/HeaterMeter/wiki/HeaterMeter-4.1-Assembly
You should be able to find the info about that build you need there.
Post back here more details about what you are seeing and somebody will help you get it going....