tesbook is the software the techs us at the dealer its wrote specially for the car so has lot of options and the ability to test all the units in the car not just read the ecu fault codes it also lest you configer the onboard computer for example the folllowing options
Daytime running lamps on or off (aka VOLVO!)
Speed locking on or off
Lazy lock and vent (using the door key only) function on or off (open windows or shuts them via key you hold key in lock or unlock and the windows open or close this is good for the summer i find)
Single point entry (one press to open drivers door, second press for rest)
Headlamp delay on or off
Tail lamp delay on or off
Number plate lamp delay on or off
Intelegent wipe (wiper speed goes down a notch under 5 mph) on or off
Programed wash wipe (no program or 2,3 or 4 wipes)
One shot down on or off
One shot up on or off (drivers window only with 4 electric windows)
i was reading the how to bit of the forum and there is a bit in ther etelling you how to test the dash like i said it says that if the test passes like you said it did the dash is fine and its more than likly a problem with one of the other modules and it gives a few more test to try and narrow it down, the below is a direct quote from that thread (might help >)
K-Bus communication to Light Switch Module (LSM)
Turn the hazard warning lamps on, if the direction indicator lamps in the instrument pack operate, then the K-Bus communications between the Light Control Module (LSM) and the instrument pack is functioning correctly.
K-Bus communication to Body Control Unit (BCU)
Open any door with the ignition switch in position 'II'; if the door open warning lamp is illuminated, then the K-Bus communications between the Body Control Unit (BCU) and the instrument pack is functioning correctly.
K-Bus to CAN-Bus gateway
Start the engine and switch the air conditioning on. Open the bonnet and monitor the operation of the air compressor clutch; if it is cycling on and off (pulley rotates then stops) then the K-Bus to CAN-Bus gateway is functioning correctly.
CAN-Bus communication to Engine Management ECMs
Start the engine, if the tachometer displays the engine speed, then the CAN-Bus communications between the ECM and the instrument pack is functioning correctly.
CAN-Bus communication to ABS ECU
For vehicles with ABS and traction control, turn the ignition on. If the traction control warning lamp or message is illuminated, then the CAN-Bus communications between the ABS ECU and the instrument pack is functioning correctly.
CAN-Bus communication to Electronic Automatic Gearbox (EAT) ECU
Turn the ignition on, if the PRNDL display in the trip computer / odometer changes gear in accordance with the gear selected, the CAN-Bus communications between the electronic Automatic Gearbox (EAT) ECU and the instrument pack is functioning correctly.
Turn the ignition switch on and close all the doors, and wait until all the large icons have been displayed. Select navigation by using the relevant navigation controls. If the navigation information is displayed in the message centre, then the NAV-Bus communications between the Navigation Control Unit and the instrument pack is functioning correctly.
ps i know i keep saying it but dont forget to check that water flows down the drain holes , i just hear alot of desils suffer thats all good luck mate but to be honest i think it will be easirer in the long run to pop this baby to a dealer, providing the battry disconect etc doesnt work get it while its early on might save a bit of cash