Here are four discussions of the question from U.S. usage authorities (or commentators) who have substantial followings.

First, from Barbara Wallraff, Your Own Words (2004) [combined snippets]:

“A TV commentator recently referred to a new software package as having been troubleshooted. Does a suitable past-tense verb exist for something that has undergone a troubleshooting process?”

Here, too, we have a back-formation: troubleshooter was the original word. (Though NOAD [New Oxford American Dictionary] calls troubleshooter a derivative of the verb, not even its big sister the Oxford English Dictionary agrees.) So the form troubleshooted is less crazy than it may sound. NOAD fails to specify that the past tense of the verb is irregular, as it does with overshoot (overshot), and its front matter doesn’t tell you to refer to the root verb (shoot)—— so it seems implicitly to be calling for troubleshooted. The RHUD [Random House Unabridged Dictionary] actually gives troubleshooted as a variant, together with troubleshot. WNW [Webster’s New World College Dictionary] doesn’t give the verb at all, past, present, or future—only troubleshooter and troubleshooting. However, the other dictionaries either explicitly or implicitly (as in, W3’s [Webster’s Third International‘s(?)] front matter does tell you to look under the root verb) are in favor of troubleshot.

Second, from Bryan Garner, Garner’s Modern American Usage, third edition (2009):

troubleshoot > troubleshot > troubleshot. So inflected. The erroneous past-tense and past-participial form troubleshooted sometimes appears—e.g.:

• “Throughout the evening she troubleshooted {read troubleshot}, greeted guests, mourned the winning low bid on a set of top-notch golf clubs placed by mistake on the silent-auction table, and worried about how the crowd was responding to the new location.” Nancy Bartley, “Far East Gala II,” Seattle Times, 16 Sept. 1991, at C2.

…

Language-Change Index[:] troubleshooted for troubleshot: Stage 1

Garner’s Language-Change Index attempts to provide a scale for measuring the extent of to