I don't want to harp on what you have tried already but in the case of grounding here are some guidlines I have discovered (mostly the hard way) over the years. I have not used the Logix5000 in particular but I have cured erratic operation and program corruptions before in A-B, Omron and GE by...
The problem is most likely that the program is password protected. You will need to know the password. If you have a hard copy or software copy of the program, look for the SYS (Fun49) instuction. Operand #3 (bottom) will be the password or the memory location for it. If it is a memory...
One area I have found that is generally lacking is wire color coding/sizing. You can go to NFPA.org and download (for a small fee) the NFPA 79 section of the manual (the entire NEC is only section 110). In NFPA 79, they specify everything for the enclosure/control wiring including colors, size...
In addition to online editing, Omron PLCs can store address symbols in the PLC memory. Granted, they need to be downloaded but when you plug into a "strange" PLC the symbol set can be uploaded with the program (assuming the previous programmer downloaded them). This makes it much...
