This case is not going to just go away. Robbery is listed as a violent felony in California Penal Code §667.5(c), which also makes it a "strike" under the Three Strikes law.
You need to contact a criminal defense attorney in the county where you were convicted and help you clear up this mess. Is is very unlikely you will be able to resolve your situation without returning to California.
The term "non-extradition warrant" is misleading. The court where you failed to complete your time has apparently issued a warrant for your arrest, making you a fugitive. If you are arrested on the warrant in Indiana, you could be held while the Governor's office in California decides whether to issue a Governor's warrant, which is a formal demand for Indiana to return you.
Following an arrest, there are procedures that vary from state to state, but most include an identity hearing to determine whether you're really the person named in the warrant, then a hearing of commitment on the Governor's warrant from the extraditing state. The process can take more than a month, and there are usually provisions to delay the process even longer if the Governor's warrant it not received.
Extradition is a nightmare. If you could drive from Indiana to Modesto in a week, extradition would probably take a month. There is no direct jail bus; prisoners being extradited are handed off between state, local and regional prisoner transportation agencies, and often have long layovers in holding facilities.
Get the best lawyer you can, but it is still very likely you will wind up spending some time in custody in California. If you just have to serve the balance of your 280 days, I would consider that a miracle.
Please understand that this is a general discussion of legal principles by a California lawyer and does not create an attorney/client relationship. It's impossible to give detailed, accurate advice based on a few sentences on a website (and you shouldn't provide too much specific information about your legal matter on a public forum like Avvo, anyway). You should always seek advice from an attorney licensed in your jurisdiction who can give you an informed opinion after reviewing all of the relevant information.
I agree with Attorney Marshalls lengthy and accurate answer. The attorney should contact probation first before attempting to go in front of the Judge. If you have vacation time saved up from your current job and/or can take a leave of absence that might be the way to go.
Good luck with your situation.