G2A responded to my chargeback. What can I do to influence paypal in my favour?

I bought a Steam Key without G2A Shield. Did a chargeback on paypal saying the code didn't work. G2A responded today. I can't see their response but is there something I can call and tell paypal or email to them so that I can swing the dispute in my favour? I've done one chargeback in the past and g2a didn't respond then.

The item in question is a 6 euro steam key. Also, the dispute status says paypal will get back to me by december 19th if they need any additional info from me but I've read they close disputes in the seller's favour without even asking the buyer for additional evidence. Even if they do ask me for additional evidence, what can I give them?

With origin and blizzard keys, we can ask customer support the time/date of activation but this can't be done for steam.