CL300 First Officer reported an inadvertent engine shutdown during cruise when the Captain dropped their cell phone on the 'Engine' panel when returning to their seat. Crew was unable to restart the engine and diverted.

Narrative

We had received an email from Dispatch in-flight asking if we could change our destination to ZZZ (filed and cleared ZZZ1-ZZZ2) to cover trips on the following day. As a crew we reviewed our fuel onboard and a new possible route and decided we could; the Captain/PF transferred controls to me and went to the cabin to call Dispatch and inform them we could; and verify they still wanted this diversion. Upon completion of the call; the Captain moved forward to enter the cockpit. While climbing into his seat; he dropped his phone which landed on the ENGINE" panel on the cockpit pedestal. I heard an engine roll back; with an associated yaw. I corrected the yaw with rudder and rudder trim changes and increased power; and visually confirmed the right engine had shut down. The Captain had entered his seat; fastened his restraints and put on his headset. I transferred controls to him; then informed ATC we needed a descent and [requested priority handling]. The Captain called for the QRH for the Engine Failure In Flight checklist and took over the radios while I worked through the checklist; diverting to ZZZ3. I prompted and he verified the correct levers; switches; etc. before making any changes. We verified the correct checklist; and completed it to secure the right engine. He then called for the Engine Airstart checklist. We determined where we were in the Airstart Envelope; descended below FL300; and began the procedure for a cross bleed start. Again I prompted and he confirmed the proper levers; switches; etc. that were to be moved before moving them. The upon moving the RUN switch to the RUN position; the Full Authority Digital Electronic Control (FADEC) commanded the start sequence; shown by a green START next to the right engine instruments. After roughly 30 seconds it was clear the engine would not start; I aborted the start and we moved to the Engine Shutdown In Flight checklist. After securing the engine; we began the Single Engine Landing checklist while in a final descent getting vectored for the ILS-XXL. The checklist was completed uneventfully; followed by an uneventful landing and exit from XXL at [Taxiway] 1. We were met by emergency crews and made contact with them; declining the need for services or to be followed to the ramp. We then taxied to FBO; shut down the left engine normally; and made contact with Dispatch and MaintenanceCause: The Captain dropping his phone; which unfortunately landed on the ENGINE panel and likely pressed the R-ENG FIRE PUSH button. Note that the cover was down at the time; and the plastic cover was not broken after the incident.Suggestions: This is not the first time on record of a similar event happening; as in training we are often told of a similar story where a pilot threw a candy bar to the cockpit from the cabin; also pressing the ENG FIRE PUSH button inadvertently. Although this is exceedingly rare; perhaps redesign of the cover could be considered. In addition; I would suggest to not enter or exit the cockpit while carrying loose articles (phones; food; drinks; etc) and to place them on the step; secured in pockets; or on/under the seat before entering/exiting the cockpit."