Cannot get Pronterface to connect to Prusa i3 Rew2ork

Over the past 18 months or so, I've been slowly building a Prusa i3 Rework from parts I have purchased from a number of internet sources. I have had difficulties in the past with software and programmes and have put the project aside and moved along with other projects (motorcycle restoration being one). That said, I have found time to devote to the printer and believe it is now at the stage of 'breathing life' into it.

I thought that I had damaged some of the electrical components (or they were faulty) so have duplicates of virtually everything (Arduino Mega 2560 board, RAMPS 1.4 board, stepper drivers, etc). Originally I had a Chinese clone of the Arduino board however I have replaced that with a genuine Italian made board now.

I digress.....I have tried to 'fire up' the printer over the past couple of days and have used Pronterface to drive the printer. I believe that my Marlin configuration.h file is pretty well spot on.
Initial attempts to get Pronterface to connect with the printer have come up with "connecting" but nothing else has occurred for more than 15 minutes. I had to adjust the serial port in Pronterface to COM5 as that is the port the laptop has assigned to the Mega 2560.

I have had a couple of Arduino updates so decided to re-verify the configuration.h and upload it to the board - it gets right through but ends up with an error message which reads "avrdude: ser_open(): can't open device "\\.\COM5": Access is denied. avrdude: ser_drain(): read error: The handle is invalid". The serial port COM5 is confirmed as the port assigned to Arduino/GenuinoMega or Mega 2560 however in configuration.h the serial port is defined as '3'.

A change of the serial port to '5' in configuration.h is not accepted in 'verify' with other error messages showing.

I'm not a computer wizz, that's for sure - I'm a pretty good dab hand at anything mechanical.

I'd greatly appreciate any advice fellow reprappers can offer to help me to get the printer alive and for final configuration before running test prints.

Cheers.

The serial port mentioned in Marlins code is used for the LCD/SD-card AFAIK, so you better keep it at "3".

There is a line, that specifies the BAUD rate in Marlin. This setting has to match with Pronterfaces BAUD rate and Arduino IDE as well.

serial port in config should read

#define SERIAL_PORT 0

Appreciate your assistance Obewan.

I altered the serial port to '0' in the configuration.h file and that solved the problem and I've been able to get the printer working which will enable me to fine tune the calibration..

Once connected, I had a problem with the hot end thermisor not reading. I replaced it and solved that problem. Seems that wires at the hot end were broken by the holding screw which had been excessively tightened.

One motor is clearly not getting sufficient power so I'll adjust the stepper pot until it quietens down. All other motors are running quietly.

Once again, thanks very much for the assistance.

Cheers