just to add, once you do all the basis math on Form 8606 I think you'll find you've already converted most of the $2700 in 2024-2025 due to the pro rata rule and paid tax on it. I think most of the $2700 balance is now in your basis (401k reverse rollover doesn't help you at this point), if my math is correct:
For 2024, 7000/9700=72.165% tax free conversion; $5051 tax free, $1949 taxable, basis carried fwd is $1949
For 2025 (assuming still 2700 but probably higher due to earnings), basis after the contribution is now 7000+1949 =8,949 so 8949/9700=92.257% tax free conversion; $6458 tax free, $542 taxable, basis carry fwd is 8949-6458=$2491
For 2026 you can convert everything to Roth and only owe tax on a $209 left plus earnings.
When you do your 2025 return the question about "made and tracked nondeductible contributions to IRA" will be Yes, and it will show the basis carried over from your (amended) 2024 return or you can you amend it if any issue.
Once you're completed the contribution and 1099-R conversion input, check the outcome on Form 8606 either in forms mode on desktop or in the PDF output to see the above calcs.
This article may also be helpful
https://ttlc.intuit.com/turbotax-support/en-us/help-article/retirement-benefits/enter-backdoor-roth-...
