dont qoute me on this but it might be little endian.
LDA op code for 5602 is A9
so you might see this 05 A9
which is actually
I just quoted you on that: it's not correct.
LDA #$05 would be A9 05. Little-endian means that when you use a 16-bit value (ie two bytes for a number) the first byte is the least significant byte (LSB) and the second is the most significant (MSB). So if you wanted to load from the address $8743 your opcodes would be A5 43 87.
I've just opened up one of the BurgerTime ROM files and instantly I can see that this is 6502 assembly (I've reached the point that I can tell it just from the opcodes
). Looking at the cheat file you mentioned, there clearly is no file named "maincpu.pb" so I imagine that's something else, but the $2B location is obviously RAM, not ROM, so you won't find that in the ROM. What you WILL find is a reference to that location, such as an instruction that loads that location with a certain number - your starting amount of lives, for instance. I'm gonna do a bit of playing around and see if I can find what you're looking for.
I'd started by looking through ROM files for references to $2B, and I did find the instruction that gives you peppers at the start, but I couldn't locate the one that takes away a pepper when you use one. But then I realised that MAME has a built-in debugger, so after five minutes on that, I found the instruction, changed it, and voila, infinite peppers!
All you have to do is open aa06.13b in a hex editor, and change $7E8 from 01 to 00.
Just for the hell of it, I then found infinite lives: open aa05.10b and change $89F from D6 to A9.
Hope your son enjoys it!