Maybe the best answer here is to get the full cable harness [https://www.ebay.com/itm/Genuine-Apple-A1407-Thunderbolt-Display-Signal-Cable-Assembly-922-9941-AD89/232532039489?epid=2255392710&hash=item3623fd5741:g:pJIAAOSwEWJZwC-s|Genuine Apple A1407 Thunderbolt Display Signal Cable Assembly 922-9941]. The cable you got is an active cable the way you can tell is look at the length of the connector housing. The longer unit is active and the shorter passive. Apple no longer sells a passive Thunderbolt 2 cable from what I understand at the Apple Stores.
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=== Update (09/24/2018) ===
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Here’s the IFIXIT guide to replace the cable [guide|112355]
Maybe the best answer here is to get the full cable harness [https://www.ebay.com/itm/Genuine-Apple-A1407-Thunderbolt-Display-Signal-Cable-Assembly-922-9941-AD89/232532039489?epid=2255392710&hash=item3623fd5741:g:pJIAAOSwEWJZwC-s|Genuine Apple A1407 Thunderbolt Display Signal Cable Assembly 922-9941]. The cable you got is an active cable the way you can tell is look at the length of the connector housing. The longer unit is active and the shorter passive. Apple no longer sells a passive Thunderbolt 2 cable from what I understand at the Apple Stores.