Error 5100 points to a "carriage jam"
The carriage is the assembly that contains the printhead and cartridges.
This error can be difficult to solve because various things can cause it.
Since this is a new printer, maybe there is some packing or packing tape that is obstructing the carriage.
Verify that the carts and printhead are installed properly.
Check the gears as best you can for any obstructions.
If the carriage moves to a center position when you open the cover as if to change cartridges, try a reset to clear the error message :
1. Turn off printer (use button, don't unplug)
2. Hold down Resume button and press Power button.
3. Keep holding down Power button and let Resume button go.
4. Press Resume button 2 times then let BOTH buttons go.
5. Green lights will flash and then stop blinking.
6. When green lights are solid, press the Resume button 4 times.
7. Press the Power button and the printer should turn off, if not, press the Power button once more.
8. Your printer should respond as normal
Sometimes you have to try this a couple of times, if you've never done it before.
If this does not work, unplug, wait 3-4 min, then re-plug in. Enjoy..