Borrowing from FoxKat's expertise, who is the Razr battery guru on this forum, you will need to charge your phone possibly for a whole entire day, using the charger that came with the phone. Do not try to turn your phone on during this charge. After a few hours, if you want to check the charging status then press the volume down for a second and you will get a battery icon showing percent of charge.
What most likely happened is that the battery got so low that it is, 1) not being recognized by the phone, or 2) so low that it may be so dead that it will not accept a charge or will take a very long time to charge. The fact that it is trying to boot up and you get the initial logo is hopeful.
Once it is charged to 100%, turn it on. Use your phone until it gets to 15%, then charge again with the phone off until it reaches 100%. After these two cycles of charges with the phone off you can use your phone as you normally would, your battery meter will be properly calibrated and you should be OK.
In the future, do not let your battery get below 15%. If your battery does drop below 15% or dies (try to never let it die) do not try to power it on till you get it charged till at least 15%.
FoxKat, please add anything or correct anything I have missed.
Sent from my DROID RAZR Maxx using Droid Forums