What would make Cena get cheered again?

I can't speak for everyone, and I'm not even sure I can give a good answer to the question, but I'll give you my reasons for booing Cena.

Ok, the 5 Moves of Doom bothers me, but I can almost over look this. Everyone has their set of moves that we see every match. Even Bret Hart, whom some would say is best there is, was, and ever will be (see what i did there lol) had his set of moves. You knew you were gonna see the elbow of the 2nd rope, the backbreaker, the russian legsweep, and bulldog in every match. The difference between the 2 is that Bret worked alot of different moves into the match where as Cena relies mostly on the 5 Moves of Doom. The other main difference between the 2 is.......

Selling
This one actually bothers me more than his limited moveset. Too often Cena forgets this key element. Sure he'll go down for a moment, but shortly after he's back to his feet like nothing happened. Guys like Bret, Shawn, even Jeff Hardy can sell their opponents moves, making the performance even more believable, and in doing so also drawing sympathy from the crowd causing the crowd to get behind them. I just don't see this from Cena.

The main reason I don't like Cena though is the fact that he's so stale. He hasn't changed anything since 2005. Same look, same moves, exact same character...the only things that have changed are his Tshirts and occasionally the color of his shorts. Looking back on other wrestlers careers, I can see how they've changed and grown over the years. I've not seen this in Cena.
When he arrived in WWE he was in his wrestling gear, then he changed to his current style of gear when he took on the rapper gimmick. The rapper gimmick was fresh and he was funny while insulting his opponents. Then they moved him to RAW and I'll admit it, I was excited to see him join RAW. I had enjoyed him during the early stages of his rapper gimmick and thought he would be the guy to lead the WWE into the next era. But although he was still funny at times, he lost the edge to his character. And like everyone else, I started to grow tired of the same old stuff that he would give week after week.

I think they're just scared to try anything new with him. They're scared the kids will loose interest in him.

Usually when I watch, I try to keep in mind that the kids are a big part of the wrestling audience. And although I'm bored with Cena, they still love him. And they have every right to be entertained as I do. So I just try to over look Cena and get enjoyment out of the rest of the show.

Personally I think its too late, fans will Boo him just because its become a fun thing to shout "Cena Sucks" at shows when he's suppose to be the face of WWE and the number one babyface, its like a fans way of sticking it to the system. Personally I think if people are going to boo him then he should give them something to boo about. I think a heel turn is in order, change the look, and get rid of those ridiculous denim shorts.

If anybody has ever seen Cena as the prototype in OVW the did some really good entertaining heel promos. Have him bust out some heel raps as well.

Last time he was getting good reactions was the latter half of 2006. Especially when he FU'd Kevin Federline.

Increase work rate & add to 5 moves of doom lulz.

He should become an anti-hero, not a full heel. Just a badass character

he is likeable but i would say change the attire to something maybe with out as many cena logos. give him more direction to lighten up with the corny and stiff talk and just be more relaxed and natural. maybe more attitude. maybe they can bring back the barbershop and he can throw someone through a window