One of the big obstacles to Hitler's rise to power had been President Hindenburg. However, with the German parliament unable to function properly due to no one party gaining enough support to govern Hindenburg had agreed to make Hitler the Chancellor of Germany which was done in January of 1933. In early 1933 the German parliament and Hindenburg passed the Enabling Act (which would expire after 4 years), which allowed the NSDAP and Hitler to issue laws by decree, and all other political parties were banned.
At this point Hitler was pretty much a dictator. The only person who still stood in his way was Hindenburg who still had the power to fire Hitler. However, in August of 1934 Hindenburg died and Hitler then took the position of Head of State along with his position as Head of Government.
What I want to know though is what plans, ideas, etc did Hindenburg have to keep Hitler, who he despised, in check, or if the need arose to toss out of government?
One thing to remember is why Hindenburg disliked Hitler so much… namely, that the loud-mouthed, rabble-rousing, movement-leading corporal seemed (to the ancient general) as being all-too similar to the Bolsheviks that Hitler claimed to be fighting against.
This is important, because Hitler was seen by the neo-conservatives (and the generals and advisors surrounding the increasingly-senile Hindenburg) as the lesser of two evils, with "Socialism" (not just the Communists, but also the SPD) as the greater evil--the real threat that needed to be dealt with.
Aside from the short-term political crisis, Hindenburg and/or Hindenburg's advisors saw Hitler as the only tool to take out the Communists and take down the Social Democrats in the long run. Which Hitler did, first thing, with the full support of the conservative non-Nazis in the cabinet. And the Enabling Act pared back the disorderly democracy that so disgusted the conservatives (and Hindenburg as well). So why try to rein in Hitler when he's doing exactly what Hindenburg/Hindenburg's advisors wanted him to do?
By the time Hitler turned more directly against the neo-conservatives six months later, it was already way too late for them to do anything about it. Hindenburg was on his death bed, and the neo-Conservatives were running scared. More importantly, hundreds of thousands of Germans were flocking to join the Nazi Party… and Nazi officials could act as they pleased, with no establishment-figure willing to risk confronting them. (Remember that Schleicher was shot in the July 1934 purge… and while Papen was too prominent to kill, they shot his secretary as a message.) Even if Hindenburg would have still had his wits about him in 1934 (which he did not), the time was long gone when a Constitutionally-given power (like that of the President to dismiss the Chancellor) could actually be useful. Everyone saw the writing on the wall… the Weimar Constitution was dead in every way except as an empty formality, and it was either join the Nazis or keep your head down.
TL/DR: Hindenburg appointed Hitler to do a job (crush the socialists, limit democracy), which he did; but none of the conservatives realized that this would give Hitler so much political momentum (and police powers) that he would thereafter be unstoppable. The conservatives were not the sharpest crayons in the box, if you know what I mean.
Sadly I've forgot to pack Joachim Fest's Hitler biography when I moved, but I remember that in order to get the chancellorship Hitler had to make one, at least from a modern perspective, incredible concession:
When he formed the government in Jan. 1933 he was only able to put two NSDAP members in his cabinet. Wilhelm Frick became Minister of the Interior and Hermann Göring was appointed Minister without portfolio. The other six members were either conservatives or could be considered part of the military establishment. Blomberg the Minister for the Reichswehr (i.e. the military) was actually appointed by Hindenburg without Hitler recommending him first, which was unconstitutional at the time.
The crucial point in consolidating power wasn't so much the Enabling Act but the presidential directives issued after the Reichstags fire. This was the point where Hindenburg gave Hitler sweeping powers including the power to suspend the freedom to assemble, the freedom of the press etc. At this point the Nazis controlling the Ministry of the Interior became vital.
Additionally Hitler did a lot of maneuvering behind the scenes to get certain cabinet members on his side, for example the aforementioned Blomberg thereby splitting the military establishment. Maybe others can contribute something about the exact chain of events that led to all major parties save the SPD voting themselves out of existence with the Enabling Act.
The exact role of Hindenburg himself is a bit of a mystery to me. What I've read indicates that he was "controlled" by a cabal of people surrounding him including his son Oscar who pushed him to appoint Hitler. Whether that is true I don't know. Anyway after the Enabling Act the President was effectively isolated and only controlled the military directly. As Hitler went out of his way to placate the generals, culminating in the so called Night of the Long Knives, he successfully prevented any real danger of a coup from the last remaining power bloc that was not under his control.