For me, post-orgasm torture is the hottest torment.  So I'd ignore his weak snapped finger and carry on rubbing his dripping cock, especially round the very sensitive cock head. Tell him it will continue until he cums again, since he can't control himself properly.   I'd also take off his gag, as I enjoy hearing lads moan and groan and cuss.  Oh, I'd of course leave the electro dildo on, maybe varying the speeds to keep him uncertain what will come next and to hear his groan as the dildo speeders up.  By the way, is it ribbed? It should be. Hot German lads need extra hard fucking aids.