Unknown driver?

My 2004 Buick Rainier cxl 5.3L AWD recently started having issues. I went to start it and it would act like it wanted to start but wouldn't. Then all of the warning lights on my dash came on. My friend checked all of the fuses and they are all ok. He did say he did something to a green printer looking cable that is located in the passenger compartment fuse box located right behind the driver's seat underneath the back seat. When he did whatever he did to that( I'm sorry I don't know what it is called) my car started but all of the warning lights were still lit up on the dash and it said "Unknown driver". Then all of the gauges on the dash stopped working including the odometer. If I turned the car off it would not start back up without messing with that green ribbon under the back seat fuse box. Can you please tell me what that green ribbon is called? What is used for? We have tried everything and checked everything we can think of and have not been able to figure out what's causing the issue. Any new input would greatly be appreciated.