My answer might not be what you'd expect but I'll try anyway.
Did you troobleshoot your serial communications ? Try doing a simple programm for both cards and try sending data from one to another.
uno code (not tested)
mega code (not tested)
Did you check your connections ? Tx (mega) to rx (uno) and rx (mega) to tx(uno)
In your setup() on your arduino mega
void setup()
{
Serial.begin(9600);
lcd.begin(16,2);
pinMode(22,INPUT_PULLUP); // Reed switch - Row1
pinMode(24,INPUT_PULLUP); // Reed switch - Row2
pinMode(26,INPUT_PULLUP); // Reed switch - Row3
pinMode(28,INPUT_PULLUP); // Reed switch - Row4
pinMode(30,INPUT_PULLUP); // Reed switch - Row5
pinMode(32,INPUT_PULLUP); // Reed switch - Row6
pinMode(34,INPUT_PULLUP); // Reed switch - Row7
pinMode(36,INPUT_PULLUP); // Reed switch - Row8
pinMode(2,INPUT_PULLUP);// Push Button
pinMode(38,OUTPUT);
pinMode(40,OUTPUT);
pinMode(42,OUTPUT);
pinMode(44,OUTPUT);
pinMode(46,OUTPUT);
pinMode(48,OUTPUT);
pinMode(50,OUTPUT);
pinMode(52,OUTPUT);
pinMode(3,OUTPUT);
digitalWrite(38,HIGH);
digitalWrite(40,HIGH);
digitalWrite(42,HIGH);
digitalWrite(44,HIGH);
digitalWrite(46,HIGH);
digitalWrite(48,HIGH);
digitalWrite(50,HIGH);
digitalWrite(52,HIGH);
digitalWrite(3,LOW);
}
I don't see the Serial1.begin(9600) but you mentionned it above.
I hope this helps, sorry if I've not solved your problem.