Thanks for the link, I'll read it fully tomorrow. But before I go to zzzzzz I had a quick scan, seems that there's a procedure to fix this and if all else fails to update the BIOS (I'm currently on A00 I think).
Funny thing is, I plugged the mini into the mains and it now seems to be ok, no flashing lights, battery appears to be charging. Fingers crossed it stays like that.
Dell Mini 9 2GB 64GB RunCore SSD BT 1.3MP 10.5.8 A05 NBI .8.3 RC3
MBP 2.4 C2D 4GB 160GB 10.6.2
Macmin 2.53 C2D 4GB 320GB 10.6.2
Macmini 1.83 CD 1GB 80GB 10.6.2
iPhone 3Gs 32GB; 2*PS3 (320/40GB + PlayTV); Wii; PS2; PSP Phat; PSP3000