An explanation of error codes can be found here. A F9 suggests a software fault.
This type of fault based on my experience will require a new control module, but sometimes can be repaired by a simple re-programme, a new module will cost around £100-120, and require to be installed by an engineer as the new modules often require programming as part of the install.
You may well find the fault clears if you leave the unit unplugged over night, however the fault will reoccur.
If you would like me to recommend a local engineer in your area, please provide your postcode.
I have spoken to the local engineers we have used in the past, and none of them have the software to programme the control board.
For this reason I suggest you go to the manufacture directly who offer a fixed rate labour repair service for £110. Which at least should allow them to re-programme the board, first, and if that doesnt work order and fit a replacement board. From memory if the model is less than 5 years old and you registered it, you will also be covered by by a free parts warranty, in which case it wont cost you anything more than their one off labour charge.
Indesit can be contacted on 03448 224 224, when promoted select option 3, then option 3 again.
Appreciate if you can rate the service received, so I may close the case.