I tried the pencil trick on the contacts, but didn't work. Finally I bought the conductive film replacement and it's all back to life. I had a hard time finding some in stock in the usual Chinese websites (like being informed two months after the purchase that there was none in stock and I'd be getting a refund). Finally I found one, allegedly shipped from the UK, on a website called fruugo. Attached are the photos of the product. Note: this specific SKU in the photo is for the DS4 v1. Pay attention to which model you have (v2 shows the LED through the TouchPad)