Little Fix in Arduino Code

I have a working code for a watt meter device I have and the I after the last freelancer made a change to the pcb (changed to a different voltage regulator and added protection diodes) the code didn't work anymore. The freelancer did a quick change in the code and it suddenly works but tons of bugs that the freelancer before him fixed came back. There was a problem that came back that the voltage is always showing round numbers and you can't show any number other than zero after the dot even when using the calibration pot, the amp draw when on idle with no amp charge changed back to being very high, there is a lag when pressing the button to change screens and lots more that was working perfectly until the last freelancer made a change to the fixed code and brought all the old bugs back. So, I'm going to give you the code that worked before the pcb hardware change and has all the bugs fixed in order to make it work as is with the new hardware and without all the bugs. I will release the milestone ONLY if it works without the bugs (after I fully test everything) since those bugs were already fixed and I just need the code to work with the new voltage regulator and small diode circuit changes to the power supply part of the device.