|Hi Waves, did the psu/battery/computer ever work ok?|
If so, have you tried (with the power off) removing/replacing the battery a few times. This cleans up its contacts.
On the battery there may be a diagram of its contacts and their voltages, which may allow there being measured, but it is not a good test only a guide.
However if you have had 1-2 years or more battery usage it may simply have worn out. Were there any low charge warnings?
Here in the UK, inexpensive oem batteries can be found on ebay or Amazon.
Do not buy the cheapest, look for one with a higher wattage than the original, with the same number (6?) of cells and 1-2 year guarantee.
e.g. I was in Italy and purchased one from an Ebay UK seller, who sent it sent to Italy. It arrived within a week and including postage, cost about a 1/3 of one from the computer maker.
As a matter of interest, where are you based? I am in Hammersmith, West London.
Good Luck - Keep us posted.