Can't get speed to go above 1mph

Please note that these instructions don't apply to all models of treadmills. Many recent models, including all models with touchscreen consoles, do not have the capability for the user to calibrate the speed.
Speed calibration is a process that is used to correct imbalances in the machine's operating speed.
Please note that this procedure involves pushing the machine to its maximum speed very quickly. Do NOT stand on the treadmill while performing this procedure.
First, you need to enter calibration mode on the console. To do this, press and hold the STOP and SPEED INCREASE buttons (this will be either an up arrow or a + (plus) symbol). While holding these buttons, insert the safety key onto the console. This will cause the machine to go into calibration mode. After this has occurred, you may let go of the buttons and the safety key.
Next, press the stop button once. This will enter advance the screen to the next feature of calibration mode. As said previously, do not stand on the treadmill while performing this procedure. Press and hold the speed increase button. Watch the console. You will see a number on the display that will increase as you hold the speed increase button. Continue to hold the speed increase button until the number changes to "85." This will take the treadmill to its maximum speed, which will also be displayed on the console. Please note that the example below only demonstrates the console displaying "85", not the treadmill's operating speed.

By increasing the incline level on the treadmill, you will increase the number of calories burned during your workouts. Incline training works the leg muscles differently and more efficiently than training on a level surface. Incline training provides a great cardiovascular workout without having to increase speed.

Here is a link to the manual pay close attention to page 16 this will tell you how to see if it is in fact in the demo mode and how to cancel it. Some thing to remember about the display is that it is a matrix with contacts going both horizontal and vertical if one is broken some buttons will work and other won't. You may want to remove the console and clean the ribbon cables.

you need to replace the key pad

I’m happy to assist further over the phone at https://www.6ya.com/expert/james_1cb31da1bc8c6102

get a new battery

You have to replace the entire console.

Add incline. Instead of keeping the treadmill on a flat surface, maintain an incline as you walk, jog or run. This will serve to replicate the wind resistance and terrain variation that you encounter when you run outdoors. Keep an incline of at least 1.5 percent on your treadmill throughout your workout.

2 Increase your speed. If you run at the same speed every time you workout, your body will not be challenged and you may reach a fitness plateau. Up your speed by a quarter-mile per hour every few weeks.

3 Vary your workout time. In order to challenge your body in different ways, variety is key. If you run for half an hour three times a week, opt for a one-hour run for your fourth workout. This will help to condition your body for endurance training, resulting in more calories burned.

4 Use intervals. Interval training can dramatically increase your calorie burn in an average workout. Instead of running at a steady pace for your entire workout, mix in sprints. Jog at a steady pace for two minutes, and then increase your speed to a full sprint for 30 seconds. Return to the steady pace to recover. Your heart rate will rise on your intense sprint intervals and stabilize on your longer recovery periods.

5 Incorporate incline into your interval training. You can use incline in the same manner that you would speed to interval train. Walk or jog at a 5 percent incline for two minutes. Increase the incline to 10 percent for two minutes and then to the 15 percent maximum for one minute. Decrease the incline back to 10 percent for two minutes and finally back to 5 percent for two minutes. Repeat this same pyramid interval a few times.

6 Wear a heart rate monitor. This will monitor how hard you are actually working as well as how many calories you burn in each workout. You can then adjust your speed and incline accordingly to maximize your calorie burn.

7 Drink plenty of water before, during and after your treadmill workout. If you are dehydrated, you won't perform as well as you can. You'll work harder and burn more calories if you're hydrated

You should have a speed arrow up & down, this increases and decreases the speed in .1 mph. Try this control and see how the unit re-acts if the speed does not adjust in .1 mph increments or it stay the same either way it sounds like an upper board issue. Go to iconfitness.com go to customer service the replacement parts put you M# and will give part# and pricing.
RULE OF THUMB: IF REPAIR IS MORE THAN THE THE PURCHASE PRICE OF UNIT DOE NOT REPAIR

It sounds like you just need some calibration. To calibrate incline, turn power on press press any incline buttons, as the incline try to change unplug the key. Now re-nsert key and incline will self calibrate,

IT IS A SPEED WARNING FUNCTION YOU CAN SET IT TO GIVE YOU A AUDIBLE WARNING IF YOU GO ABOVE YOUR PRE-SET MAXIMUM SPEED