07 s60 issues with immobilizer and p0600

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trying to get this car to pass inspection for a friend who has no money at all to spend on mechanics and extra parts. I'm trying my best to learn what I can and do as much as possible before I have to make her spend money that she doesn't have. At the same time I started helping her the key fob did break into pieces and then it wouldn't start and I get the "start prevented" message on the dash. soon enough I found out its because I needed to have the piece that still contained the RFID chip from the fob to get it to start but even when holding that chip close to the ignition the car often will not crank at all or will crank twice and die again. it seems when I am slower to turn the key from the off position all the way forward it is more likely to crank and precede to then start rather then doing it quickly as most of us do in our normal drivers. With that said the code that appears on a cheap scanner from AutoZone is a P0600 for a serial communications link, but on a more expensive scanner from a some what buddy at a shop pulled up 2 different codes "710B" and "6140". I'm more worried about the 710B as it shows for the immobilizer which I clearly have been having a problem with. My first question, is the 710B a more in depth description of the P0600? Are they related? Is it possible the RFID chip got damaged when the fob broke apart? its still pretty well encased in a piece of the fob with plastic so I wouldn't think so. I've read on other forums that the computer can loose the key signal and it needs to be reprogrammed to the car but if that was the case wouldn't the car refuse to start at all. I haven't asked her if she had this problem before the fob broke though. I've checked all the fuses and they were all good. If these two codes are not the same then I guess I need to start checking the connections to the ECM and TCM as well as to the CEM? and one other thing someone with similar issues with the immobilizer under another topic got to the point where they were needing to check the DEM resistors and capacitors and when they unplugged the DEM the immobilizer messages were going away on the dash. I don't understand what the DEM does or how it corresponds to the immobilizer but at the end it seemed he just needed to repair the DEM or replace it to solve his issue. I'd be extremely grateful for any help or information on this. edit: going back through my photos the cheap scanner did have the code in the "Volvo OEM enhanced" rather in the "global OBD2 Volvo" only showed the P0600.

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