DH8 pilot reported an engine fire warning in flight after the aircraft had been in storage. The crew shut down the affected engine and returned to the departure airport.

Narrative

I was the pilot not flying (PNF) flying Aircraft X a Dash 8-400. We departed ZZZ from Runway XX with two crew members (no passengers) on board for a ferry flight bound for ZZZ1. The aircraft was operating on a FAA Ferry Flight Permit; as it had been in storage at ZZZ for several months. During this time; a third party was contracted to maintain the required maintenance schedule for the aircraft. Prior to our departure contract maintenance had just completed a power assurance check and all was deemed OK for the ferry flight.After departure we contacted ZZZ Departure and we flew the obstacle departure procedure for Runway XX. Departure gave us a vector and climb. While in the right turn and climbing through 7-8;000' onto the new heading; we experienced a No.1 BLEED HOT Warning. The bleed air switch for the NO.1 Engine was turned OFF as per the QRH. We discussed briefly how this failure would impact our flight to ZZZ1 and we decided to continue as planned. Approximately 2-3 minutes later; after getting a clearance to fly direct to ZZZ (VOR); another Master Warning illuminated; Check Fire Detect and the NO.1 Engine Fuel/Fire Handle was illuminated. I [advised ATC] that we had a No. 1 engine fire and would like to return to ZZZ airport. ZZZ gave us a descent to 10;000' and a turn back towards ZZZ. We shut the number 1 engine down and secured it as per our SOP and QRH. The pilot flying (PF) in the left seat; took over the ATC communications and flew the aircraft; while I completed the remainder of the QRH check-list.We advised ATC that there were two crew onboard; our remaining fuel and that there was no hazardous cargo.We completed the QRH Descent and Approach check-lists and discussed the landing Flap setting (15) and Vref for landing. We flew a visual approach for Runway XX at ZZZ and landed at XA:22. Crash Fire Rescue vehicles followed us down the runway until we stopped. The fire crew examined the aircraft to ensure there was no fire; smoke; or leaking fluids. We were told nothing appeared abnormal; so we released the Crash Fire Rescue trucks and taxied to the apron where we shutdown the aircraft.The crew opened up the left engine nacelle to check for damage and after a short time discovered that a borescope inspection cover for the high pressure compressor case was lying on the bottom of the nacelle. This missing cover allowed extremely hot gases to exit the engine case and blow onto the Bleed Temperature sensor and the Engine Fire Loop; triggering the Hot Bleed and Engine Fire Warnings. No evidence of an actual fire was discovered. No other obvious damage was discovered at this time.