Help With Hot Tub

So basically I fried the board on my hot tub (oops) and rather than buy another one I want to use a microprocessor with a high temperature thermistor and either a Bluetooth adaptor or a network adaptor so I can control it with my phone. Basically my thought is to have contactors operated remotely by temperature. Problem is that I'm clueless, so I'm asking for some general guidance on what I should buy to get this idea to work and I can figure it out from there.

This is not at all a job for someone who describes himself as clueless.

Save some lives and hire a contractor.

make a drawing of all your bits. motor, switches, heaters, etc.

figure out what the control board did, and what the bare minimum in has to do.
nearest I can figure, is you have a water heater that has to control to a setpoint
you have a blower to add air, a pump to pump water.
all set by switches.

once you have the absolute minimum, figure what parts you need to make that happen.
we can help if you know voltages and power requirements. hint motor nameplates offer that data.

you may already have relays, temperature sensors, etc.

as a simple point of fact, it is not possible to have a hot tub on this planet, that is open to the atmosphere, and ever need a high temperature sensor. water at sea level will boil at 100C and after that you have hot air, or a hot basin, but not a hot tub. a DS18B20 sensor will easily work over 100C.

if you live in the States, you can check CraigsList and get hot tubs, the whole thing. for free, IF you can cart it away.
if you get one for free, you can offer yours for free and have someone else take it.

I have to agree with Jremingotn about the skill level. interfacing with 230 volts should not be done by someone who is not a licensed electrician.

Okay let me rephrase. I'm clueless when it comes to microprocessors. Basically I'm looking to switch one contactor off of a remote temperature setting and two contacters operated off of a remote switch. If I were to guess I'd need a thermistor, a control board, a few relays, a power supply, transformer, a network adapter, and a GUI to run on android. But there are so many products on this site and I'm not familiar with any of them.

re-read post 2.
when you are done your sketch, things will be much clearer.
you need to put order into the confusion.
as you lay out what you have, what you need will come into focus and the decision will present itself.

I will offer that an UNO will handle most of hte job, but, if you need to get more, the cost to replace it will be another decision that presents itself with clarity as the confusion falls away.

You also need to address the need for several features such as an interlock so the heater can't come on if the pump is not running (many hot tubs have a vane in the pipes that moves when there is a water flow and operates a switch). You also need a secondary overtemp switch so that if your control fails, it still will not let the tub go above 105F for example.