A further non technical long-shot which works with some camcorders is to give a jolt to the bottom of the camcorder, as this type of action can occasionally trigger a sensor contact thats not quite fully activated. (a common fault with D & three digit models)

The problem is with this type of fault is that when no error code number is being shown on the LCD its impossible to pinpoint the location of the trouble, as it can range from a faulty cassette jamming the mechanism to a mechanism position sensor that has failed to operate during or after an operation, like loading or unloading. If you have already tried the battery out, wait a minute then reinsert again, and this has not made any difference then you could try pressing "slightly" on the cassette loading door in case this hasnt returned exactly to its normal position. Also if not already done, try operating it with the power adaptor connected and switched on, as that gives a very slight voltage edge over the battery on its own which can "sometimes" help overcome a problem, depending what of course!