That is very specific, I doubt you will find it here, most of Broken 1070 are most likely RMA'd and sent back to manufacturer.
Did you try to search your local Goodwill?
If you're just want to play with it, try to find broken GPU PCBs on Ebay, while it's not exactly a 1070 it costs less than 1070.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR0.TRC0.H0.XBroken+GPU.TRS0&_nkw=Broken+GPU&_sacat=27386&LH_TitleDesc=0&_fsrp=1&_osacat=27386