John Chen clearly relishes a good challenge but he may never have taken on a task as daunting as turning around BlackBerry. Barron’s spots a new research note from William Blair analyst Anil Doradla, who says that Chen’s comeback plan is the business equivalent of “quadruple bypass surgery” — in other words, it will be a highly complex procedure that’s fraught with peril. That said, Doradla thinks that Chen’s plan is well thought out enough where it just might have a chance to succeed. “In changing the incentives for the salesforce, aligning the company around end-customer needs, focusing on its core strength of security, and de-emphasizing its hardware business, Mr. Chen announced dramatic changes and came across as a skillful doctor conducting a