Would tinnitus be explained by perpetually-bent/opened hairs in the cochlea?
What you're describing would likely cause hearing loss, which could later result in tinnitus, but not by the mechanism you describe.
Hair cells transduce sound via remarkably fragile connections between stereocilia. The channels are closed until tension pulls the channels open (see Fettiplace 2011 for a review that covers pretty much all of sound transduction including a detailed description of the tip links and channels involved). Disconnection would result in the channels being perpetually closed, not perpetually open.
Anything like the trauma you describe would irreversibly damage the tip links and sound transmission would fail. There are mechanisms in the ear to prevent this sort of damage, but for sufficiently loud sounds the damage is not avoidable.
@AliceD has another excellent answer on tinnitus specifically here for more realistic mechanisms proposed for tinnitus: What is the mechanism behind tinnitus?. These are all centrally derived in some way. In short, the absence of proper input to the auditory processing parts of the brain results in compensation that induces an illusory perception. Similar sensations are experienced in other parts of the body as well, such as phantom limb.

Fettiplace, R. (2011). Hair cell transduction, tuning, and synaptic transmission in the mammalian cochlea. Comprehensive Physiology, 7(4), 1197-1227.