Well, you have a 40 amp minimum circuit.
Does the unit list a MAX circuit? I presume not. A too large circuit is not your problem. An appliance will only use what it needs concerning power.

You either have a problem with the terminations between the power source or the oven itself. I would remake the connections to be sure the joints were made well and are a good connection. (turn off the power first). If you have a voltage meter, check the voltage wile you are there. 120 volts from each hot to ground or neutral and 240 from hot to hot.

If that is ok, then it is a problem with the oven.

Thanks, makes some sense to me and I'll try it. Question: Why would it operate for close to 45 mins then shut down?
PS the door is stil electronically locked! Very confused!

Are you sure the current breaker is a 60 amp double breaker for a kitchen oven service (each side marked as 60 amp)? This would be very unusual I think. 40 amp oven service would be a double breaker (40 amps @ 240 volt) each leg of which would be marked "40 amp". If you really had 30 amp service then you may have burned up a loose connection in the J-box behind the oven, the wire itself being protected by the breaker.

do take note of rdtompki's post. I did not give thought to what some folks misunderstand about 2 pole breakers ( a 2 pole 30 does not equal 60 amps). Be sure of the circuit rating.

and yes, a 60 is unusual but still a possibility.

One reason the door could still be locked and the heat off is you may have lost one "leg" of the power. That would still leave 120 volt power (possibly what the control circuit uses) and the thing stayed locked waiting to heat up. If you don;t have 240 (both hot legs) the oven isn;t going to heat.

OK, it seems that everyone thinks this is a connection error at the J-Box. I did get the door open (FYI: on the JennAir there is enough room between the upper and lower to put your fingers in and manually move the latch. If it is the upper you have to have pretty small fingers but I assume its possible).
I took a look at the breakers again; squareD brand, double pole, 50 each. I'll let you know what I find at the J-Box.

took a look at the breakers again; squareD brand, double pole, 50 each. I'll let you know what I find at the J-Box.

That is not an each. It is one breaker rated at 50 amps. I hate it when they actually put it on both arms. It does tend to confuse those not in the know. It would still not be the problem.

I would look at the connections and then the breaker itself. Measure for voltage from each terminal (on the breaker) to neutral or ground and then from one to the other. The first should read ~120 volts and the second ~ 240 volts.

OK go it!! Thank you all!! Loose conection on the ground at the J-Box, rewired with larger wirenuts, taped everything and carefully put the J-Box back, slid the oven back in place and presto! works like a charm!
You don't know how greatful I am, I thought I blew up a couple of thousand bucks!

always good to hear success stories BUT the ground wire being loose shouldn;t have made a difference. The geound wire is only a safety circuit for short circuit protection.
Be sure the ground is connected to ground and the neutral is connected to the neutral. They will work if reveresed but can cause a safety situation.

I suggest that the ground was not the bad connection that caused the failure but it is irrelelvent if you got the thing cooking again.

So where's our chocolate chip cookies as a thank you??

I have a 220 line that was used for an electric cook top (the cook top has been removed and no longer being used). The line is connected to a 50 amp circuit (in the panel box is a double breaker with each side marked with a 50). I now want to use that same line for the sole purpose of connecting a steamer oven which requires a power supply of 240 VAC 60 Hz 15A, 240V.
Can I use the same power supply (both the cable and the circuit breaker)?
Are there any potential problems with running a 15 amp appliance on a 50 Amp circuit?
Thanks in advance for your advice.

You need to change the 50A DP breaker to a 15A DP breaker. You would then be running a 15A device on a 15A circuit. The thicker wire, probably 6/3, is irrelevant.

ditto. you might have trouble finding a 15A breaker that you can fit larger wires in tho, maybe try a 20A but still might be tough. you don't want to protect a 15A appliance at something that will let it burn up tho. might be a tough find. if you cant find a breaker you might have a good case for cutting a few strands off the bigger wire till it just fits into the 15A breaker (gasp!!) if you keep enuf strands to more than equal a size 14g wire you should be okay. did i say that?

I have the same issue, I had an old electric cooktop that I just converted to gas. The old cooktop ran at 220V with a double breaker. Two heavy (large) wires to the panel. I replaced the double breaker and put in a single 15A breaker. My question is what do I do with the "other" heavy wire? Is this to go to the ground on the panel? Can I "splice" the wire (use a wire nut from the large wire to a smaller wire and ground that one to the panel?)

If the old cooktop was straight 240V and no 120V, (you say two large wires running to the panel), then just take the large white wire that formerly went to one of the two double breaker legs, and connect it to the neutral bus in the panel. Leave the ground wire alone. If there is no ground wire, you should add one or rewire the circuit.