1) You must amend your 2015 tax return to show a $5,500 nondeductible traditional IRA contribution and no Roth conversion (unless there was some other Roth conversion that did occur in 2016). TurboTax will prepare an amended Form 8606 showing on line 14 the basis that carries forward to your 2016 Form 8606 line 2.
2) The distribution from the traditional IRA that funded the Roth conversion occurred in 2016, so it must be reported on your 2016 tax return. You should have received a code 2 2016 Form 1099-R for this if you were under age 59½ and the conversion was handled by your traditional IRA custodian.
