When is resuscitation attempted

The 5 signs of obvious and irreversible death:

To figure out who is too dead to be saved, emergency responders look for five signs of irreversible death:

Postmortem lividity
(a.k.a. livor mortis/hypostasis) which Jimi would have displayed if he had been dead for hours

Postmortem rigidity
(a.k.a. rigor mortis) which Jimi would have displayed if he had been dead for hours

Burned beyond recognition


Further information:
CPR is only performed on bodies that have just died

More notes:

When not to perform CPR
"Rigor Mortis is the stiffening of the body after death and normally appears within the body around two hours after the deceased has died. Once the contracting of all the body's muscles has taken place this state of rigor - technically referred to as the Rigid Stage - normally lasts anything from eight to twelve hours after which time the body is completely stiff; this fixed state lasts for up to another eighteen hours... in such cases...CPR that has no chance of success in terms of survival is pointless..."

When is it too late to perform CPR

Withholding resuscitation

Information about rigor mortis / livor mortis

"Livor mortis starts in 20–30 minutes, but is usually not observable by the human eye until two hours after death. The size of the patches increases in the next three to six hours,..." - Wikipedia.  So it obviously wasn't observed, meaning Jimi wasn't long-dead and he was sent to the Emergencies ward for immediate assistance.

"Starting between two and six hours following death, rigor mortis begins with the eyelids, neck, and jaw.
Rigor mortis then spreads to the other muscles, including the internal organs, within the next four to six hours."
- Wikipedia

"Rigor mortis is one of the signs of irreversible death and is an obvious justification for not starting cardiopulmonary resuscitation" Source

If a person has been dead for under 2 hours, the visible signs of rigor mortis and dependant lividity might not easily be detected. THIS is why the ambulance crew and the Emergencies doctors went ahead with CPR, in case Jimi had only passed away moments earlier.