Volvo: Volvo S80 Warning messages/starting problem, volvo s80, service req

Question
Hi. I've a T reg S80 and recently when I start the engine one of two/three things happen.1 When the key is turned, A clicking noise is heard before the engine kicks in, as if the battery is flat.I've charged it but it still occurs. 2 A warning message appears - " Brake failure-Urgent service req'd (or something similar).When I switch off and then restart, that message is then replaced by " ABS system service req'd (or similar)which then disappears when I've been driving for a while. The brakes all seem fine. The warning lights which appear are the ones relevant to the message - ABS/Handbrake etc. Could it be that the battery is on it's way out, or does the on-board computer need something doing to it? Thanks for any advice before I book it into a garage, so if I have to, I can advise them what the possible problem is. Thanks. Alex

Answer
Alex,
I would start by having the battery and charging system tested. A battery can show 12 volts but not have the ability to engage the starter.
After knowing that the battery and charging system are working properly and the warning lights for the brakes is still on, check the fault codes and see where they leed. The ABS system may need service, and that system is electrical operated, so have those codes read and see what they are.