You are on a forum, not texting, so let's go for full sentences so we can understand what you're saying -- otherwise, we can't help you.
That said,
did you try holding the mode button on your wheel base until the light changes colors to see if that helps?
Also,
when trying to calibrate your pedals in-game, does pressing the clutch register as a throttle input? If so, then you have your pedal mode switched (you've switched your clutch and throttle), and you'll need to hold the mode button in on your wheel base until the light changes color.
An RMA is a "Return Merchandise Authorization," which means the manufacturer has authorized you for a warranty return/replacement.
The potentiometer is what reads the throttle input (also used on the clutch and brake). This is literally the same thing as a volume control on a radio -- it's a rotary sensor that is used to detect the position of your pedals. If the potentiometer is broken, or if your pedals aren't working properly, you'll need to file a warranty claim with Thrustmaster and they will issue you an RMA number, or send you a new set of pedals.
Usually you have to register your device with the Thrustmaster Support site, and scan in a copy of your receipt or bill of sale, and Thrustmaster Support will often ask you to upload or send them a video showing the actual problem (so maybe something showing your pedals next to your screen or monitor showing that there is no input when you press the throttle).
See how much clearer things get when you communicate with whole sentences?
