My nexus was constantly popping up with a no sim error and making me restart 2-4 times a day and then would have poor signal during this time before and after restarts. I went to the store and they refused to give me a new one because they could not see the issue (well duh lol). Well long story short I popped it in my thunderbolt using a micro sim adapter and used my thunderbolt for about 15 minutes. I then put it back in my nexus and ever since then I have not once seen this error in the last 3 weeks and have had excellent signal since! So the moral of this story is see if you can use your sim in another 4g phone of yours because nothing happens to your plan or anything and it might help you with this issue as well. Just wanted to give this tip to help others on this excellent forum that never ceases to help me!