Changed the front break pads on Audi 2000 A4 1.8t and break work fine, break fluid level is fine, but have continues flashing break light. Any ideas???

Are there any DIY guides out there to replace this? It sounds as though it's a common deal (which also plagues my TT). I don't feel that I can justify paying $1000+ for a new one, when I could possibly do it myself?